Communication Macromolecular Rapid Communications https://www.doczj.com/doc/2417790170.html, 895DOI: 10.1002/marc .201300831light-emitting devices (WLEDs) by high-throughout solu-
tion processing, such as roll-to-roll or inkjet printing tech-
niques. [7,8] To achieve the fabrication of such devices, a core issue is to construct optical nano-inks that consist of high-quality and emission color-tunable semiconducting polymer nanoparticles (SPNs) via nano-engineering. [9]
The nanoparticle chemistry of conjugated polymers
affords diverse preparation methods [10–13] and modi? ca-
tion strategies, such as doping, [14]nanocomposites,[15]
encapsulation, [16] or surface modi? cation, [17] to con-trol exciton behavior and energy transfer. [18,19]Gen-erally, white-emitting polymer nanoparticles can be achieved by manipulating ? uorescence resonance energy transfer (FRET) via controlling intraparticle or interpar-ticle doping. [18,20,21] However, with regard to the exten-
sive application of biomedicines, [11,18,22–25]conjugated
poly m er nanoparticles (CPNs) for organic devices, [20,26–29] especially WL EDs, are severely lagging since the pio-neering exploration of polymer light-emitting devices (PL EDs) and polymer solar cells (PSCs) by Scherf and co-workers. [26,27] Fréchet et al. demonstrated a site isolation approach to control the energy transfer of encapsulating nanoparticles for WL EDs. [21] For the blue-emitting prop-erty of poly? uorenes (PFs) nanoparticles, [10,11] Tuncel et al. S upramolecular poly? uorenol enable assembly into conjugated polymer nanoparticles (CPNs). Poly{9-[4-(octyloxy)phenyl]? uoren-9-ol-2,7-diyl} (PPFOH)-based supramolecular nanoparti-cles are prepared via reprecipitation. PPFOH nanoparticles with diameters ranging from 40 to 200 nm are obtained by adding different amounts of water into DMF solution. Size-dependent luminescence is observed in PPFOH-based hydrogen-bonded nanoparticles that is different from that of poly(9,9-dioctyl? uorenes). Finally, white light-
emitting devices using CPNs with a size of 80 nm exhibit
white emission with the CIE coordinates (0.31, 0.34).
Amphiphilic conjugated polymer nanoparticles are poten-
tial organic nano-inks for the fabrication of organic devices
in printed electronics.
H ydrogen-Bonded Supramolecular Conjugated Polymer Nanoparticles for White Light-
Emitting Devices
J in-Yi L in ,J enIt W ong ,L ing-Hai X ie ,*X iao-Chen D ong ,H ui Ying Y ang ,*W ei H uang *
D r. J.-Y. Lin, Prof. L.-H. Xie, Prof. W. Huang C enter for M olecular Systems and Organic Devices (CM SOD), Key Laboratory for Organic Electronics & Information Displays (KLOEID) and Institute of Advanced M aterials (IAM ), N anjing University of Posts and Telecommunications, N anjing 210003,P .R.China E-mail:i amlhxie@https://www.doczj.com/doc/2417790170.html,;iamwhuang@https://www.doczj.com/doc/2417790170.html, D r J. Wong, Prof. H. Y. Yang
P illar of Engineering Product Development, S ingapore University of Technology and Design, S ingapore E-mail:y anghuiying@https://www.doczj.com/doc/2417790170.html,.sg P rof. X.-C. Dong, Prof. W. Huang J iangsu-Singapore Joint Research Center for Organic/Bio- Electronics & Information Displays, Institute of Advanced M aterials,N anjing Tech University N anjing 211816,P .R.China
1.I ntrod uction L ow-cost, large-area, and solid-state light sources have attracted much scienti? c and industrial interest in the background of the energy crisis. [1–6] One appealing and potential method is ecofriendly nanoparticle-based white Macromol. Rapid Commun. 2014, 35, 895?900
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J.-Y. Lin et al.
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896demonstrated CPN-based WL EDs with CIE coordinates of (0.28, 0.34) by controlling the photochemical cross-linking
reaction to tune low-band emission at 530–550 nm. [28]In this context, it is signi? cant to explore delicate methods
for white-emitting conjugated polymer nanoparticles. Herein, we constructed hydrogen-bonded supramolecular
conjugated polymer nanoparticles (SCPNs) with size-dependent luminescence for WLEDs. S ize-dependent luminescence is the typical feature in inorganic quantum dot and nanoparticles when the size is smaller than the critical exciton Bohr radius. However, organic or polymer nanoparticles with the feature of the size-dependent emissions have not been observed in the literature systemically. [27,30–33] For example, poly(9,9-
dioctyl? uorene) (PFO) nanoparticles have been obtained via reprecipitation, and demonstrated optical properties similar to bulk ? lm. [30] One reason is that polymer semi-conductors have intrinsic split energy levels. Besides, the
other reason would be the driving force for the formation
of CPNs, namely weaker hydrophobic and π–πstacking
interactions. [10,11] An alternative is to explore size-dependent FRET processes. Supramolecular approaches allow for not only affording robust non-covalent driving forces to make high-quality nanoparticles, but also manipulating exciton and FRET behaviours by subtle arrangement of chain packing during assembled aggre-gation. [34] As a result, supramolecular conjugated poly-mers (SCPs) are an appealing molecular building block for
self-assembling into nanoparticles with stimuli-respon-
sive luminescence changes that have obvious advan-
tages over general conjugated polymers. [35] Herein, we designed a poly{9-[4-(octyloxy)phenyl]? uoren-9-ol-2,7-
diyl} (PPFOH) bearing hydrogen-bonded supramolecular steric carbinols at the 9-position of poly? uorene (PFs) as
a state-of-the-art model of SCPs to demonstrate distin-guished supramolecular assembly and intriguing par-ticle-size dependent behavior. PPFOH
can assemble into high-quality nano-
particles via reprecipitation. Further-
more, its amphiphilic features make
PPFOH aggregate emissions with the
green–yellow color that are combined
with blue light-emitting backbone of
PFs acting as host to compose a perfect
FRET nanosystem. As a result, the size-
dependent emissions of the hydrogen-
bonded SCPNs were observed that offer
an unprecedented alternative strategy
for WLEDs. Devices with the con? gura-
tion of Au/ p -SiC/PPFOH nanoparticles/
ITO exhibited stable and puri? ed white emission with the CIE coordinates of (0.31, 0.34). 2.R esults and Discussion
2.1. S ynthesis and Characterizations of PPFOH and PPFO8
P PFOH, together with controlled poly{9-(octyloxy)-9-[4-(octyloxy) phenyl]? uoren -2,7-diyl} (PPFO8), were prepared
according to our previous work (Scheme 1 a ).
[ 35 ] Gel permea-tion chromatography (GPC) shows that PPFOH has number-average molecular weight (M n ) and polydispersity index
(PDI) of about 5.4 × 10
4 and 1.46, respectively (Figure S1 in the Supporting Information). The control sample PPFO8 had
M n of 6.92 × 10 4 and PDI of 1.62. As showed in Figure S2, the peaks at 3550 and 3450 cm
?1 in the Fourier-transform infrared (FT-IR) spectra of PPFOH powders, involving
hydroxyl groups, suggested both free hydroxyl groups and
association of hydroxyl groups. The solubility of PPFO8 is similar to poly(9,9-dioctyl? uorene) (PFO) that exhibits excel-lent solubility in common organic solvents such as chloro-form (CHCl 3
) and toluene, but extremely poor solubility in N ,N -dimethylformamide (DMF) due to the larger difference of solubility parameters between PPFO8 or PFO (9.5) and
DMF (12.1).
[ 35 ] In contrast, PPFOH exhibited good solubility in DMF that probably contributed to its slightly amphiph-ilic feature and the formation of hydrogen bonds between
hydroxyl groups and DMF molecules. As a result, amphiphilic
PPFOH–DMF complexes are favorable for assembling by the control of external conditions, such as the addition of poor solvent. [ 12,36,37 ] However, the controlled PPFO8 is insoluble in DMF with poor capability of supramolecular assembly.
P reparation of PPFOH Nanoparticles
N anoparticles of PPFOH were achieved by the reprecipita-tion method. Size-controllable nanoparticles were obtained Macromol. Rapid Commun. 2014, 35, 895?900
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2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim S cheme 1. a ) Synthetic routes of PPFOH and PPFO8. b) PPFOH nanoparticles obtained via re-precipitation, together with the photographs of nanoparticle suspensions by expo-sure to UV 365 nm. PPFOH nanoparticles consist of random polymer chains (host) and hydrogen bonded aggregates (guest).
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by adding H 2 O into DMF solution. Colloidal nanoparticle suspensions exhibited a milky white color owing to light scattering compared to pristine colorless DMF solution (Scheme 1 b ). The general PFO nanoparticles were prepared via a two-steps reprecipitation as follows: dilute tetrahy-drofuran (THF) solution was added into poor solvent (H 2O ) and the THF was removed via heating under ultrasonica-tion. The number density of CPNs in the suspension was too low and it could not be spin-coated to obtain high-quality nanoparticle ? lms. [ 10,11 ] In contrast, for PPFOH it was hard to obtain nanoparticles via two-step reprecipi-
tation but rather by direct precipitation under the same
preparation conditions. The sizes of PPFOH nanoparticles can be tuned from 40 to 200 nm by controlling the ratio of DMF:H 2 O . The sizes were determined to be about 200, 120, 80, and 40 nm at ratios of 300:6, 300:10, 300:20, and 300:50, respectively (Figure 1 ). The diameters of these nanoparti-cles were determined by dynamic light scattering (DLS) to be about 600, 170, 100, and 70 nm (Figure S3). In considera-tion of the kinetically frozen processing of reprecipitation, it is reasonable to explain that the diam-
eter of colloidal nanoparticles decreased
with the increasing amount of added
H 2 O owing to the increased number of
nucleic cores. [ 36,38 ] The diameters in the
DL S analysis larger than those obtained
from SEM images can be explained by
the swelling effect of nanoparticles in
dispersion. In constrast, the controlled
PPFO8 could not assemble into nano-
particles via this method. These results
suggest that supramolecular function-
alization by tethering hydroxyl groups
on the polymer backbones affords an
effective approach to improve the capa-
bility of supramolecular assembly of hairy-rod conjugated polymers into size-controllable nanoparticles via the
formation of amphiphilic polymer–sol-
vent complexes. In contrast to PPFOH
powders, for the PPFOH nanoparticles,
only the lower wavenumber at 3400
cm ?1 involving hydroxyl groups was
found in the FT-IR spectra, indicated
that only association of hydroxyl groups
existed in the nanoparticles (Figure S2).
In this context, there existed stronger
hydrogen-bonding interactions in the
nanoparticles than in the powder state,
which would result in stronger energy
transfer. Meanwhile, SEM analysis was
explored to investigate the stability of the nanoparticles in suspension. We
used nanopaticles with a diameter of
80 nm as an example. In Figure S4, the diameter of pristine nanoparticles was about 80 nm. For the nanoparticles suspension with aging of 0.5 h, the diam-eter was about 80 nm, similar to pristine nanoparticles but exhibiting aggregation. With prolonged aging to 2 h, the diameter was maintained at 80 nm but further signi? -cant aggregation was demonstrated. Thus, there was not growth of the nanoparticles in the suspension with pro-longing aging time, but aggregation of nanoparticles was exhibited.
2.2. S teady and Transient Optical Properties of PPFOH Nanoparticles
T he optical properties of PPFOH nanoparticle suspensions were investigated by electronic absorption spectra; the steady-state and transient photoluminescence (PL) spectra are shown in Figure 2 a , S5, S6, S7 and Table S1. PPFOH in DMF solution (< 0.1 mg mL –1 ) has the maximum absorb-ance peak at about 390 nm that is probably attributable to Macromol. Rapid Commun. 2014, 35, 895?900
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2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim F igure 1. S EM images of the PPFOH-based nanoparticles. PPFOH nanoparticle suspen-
sions with the condition of DM F: H 2O =
300:50 (a), 300:20 (b), 300:10 (c) and 300:6 (d). The scale bars represent 200 nm. e) Diameters vs. the amounts of H 2
O . DMF solution: 1 mg mL –1 ,
300 μL. F igure 2. P L spectra and CIE coordinates of PPFOH nanoparticles suspension with dif-
ferent sizes: a) PL spectra, and, b) their CIE coordinates. All dataa were collected with
excitation at 380 nm.
J.-Y. Lin et al.
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the main chains of poly? uorene (Figure S5). The PL spectra
of PPFOH in dilute solution have three emission peaks at
419, 443, and 472 nm that were assigned, respectively, to
the 0–0, 0–1, and 0–2 intrachain singlet transitions of the
poly? uorene backbone. [ 39 ] Three emission peaks exhib-
ited a single-exponential ( 1 A *) decay, and their lifetimes were about 400 ps corresponding to three peaks of the poly? uorene ? uorescent spectrum (Table S1). [ 40 ] The emis-
sion spectra of PPFOH nanoparticles exhibited two energy regimes: blue emission at 440–460 nm and green–yellow at 530–540 nm; this was dramatically different from the
pristine PFO nanoparticles prepared via reprecipitation without green–yellow band emission,
[ 41 ] but similar to the nanoparticles of amphiphilic oligo? uorene or poly? u-
orenes, suggested the existence of aggregates.
[ 12,36,37 ]For nanoparticle suspensions obtained via reprecipitation, emission peaks at ca. 460 and 535 nm had lifetimes of ca. 112 ps and 2.92 ns (Figure S6 and Table S1), affording evi-dence for the aggregates rather than ? uorenone, according to previous investigations. [ 42–44 ] These assumptions are supported by the FT-IR spectra in which the feature peak
of ketone at 1720 cm ?1 was not observed (Figure S2). It can
be deduced that the aggregate species, together with the
pristine poly? uorene chains in nanoparticles, consist of a
self-doping energy transfer host–guest nanosystem.
S ize-dependent emissions of PPFOH nanoparticles have been observed in Figure 2 and S7. For nanoparticle
suspensions obtained via reprecipitation, the intensity of green–yellow band emission was increased with the decreased size of nanoparticles (Figure 2 a ). For reprecipi-tation with the frozen process, the intensity of green–yellow band emissions is associated
with the amount of aggregates. This
can be explained by a proportional
relation between the number of nuclei
and the amount of aggregates with
increasing amount of H 2
O . From Figure S7, the intensity of green–yellow emis-
sion of PPFOH nanoparticle ? lms spin-
coated from nanoparticle suspension
also increased with decreasing size of
nanoparticles, and was stronger than
the intensities of the corresponding
nanoparticle suspension. PPFOH nano-
particle suspension and ? lm with diam-
eter of 200 nm exhibited blue emission
with the CIE coordinates (0.17, 0.16) and
near-white emission with CIE coordi-
nates of (0.24, 0.33), respectively. PPFOH
nanoparticle suspensions with size
of 80 nm exhibit white color with CIE coordinates (0.30, 0.42) but slight green color with CIE coordinates (0.29, 0.48). The particle thin ? lms exhibited similar size-dependent photoluminescence with high intensity of green emission with reduced particle size. The intensi-ties of green–yellow emission of nanoparticle ? lms spin-coated from suspension was stronger than those of the corresponding nanoparticle suspensions. Size-dependent photoluminescence offers an alternative ?
exible method to tune emission colors.
2.3.E lectroluminescence Properties of PPFOH Nanoparticle-Based WLEDs
H ybrid WL EDs with the con? guration Au/ p -SiC/PPFOH nanoparticles/ITO were fabricated in order to explore the potential applications of nanoparticles thin-? lm devices (Figure 3 ). According to previous works, [ 45–48 ] the electrolu-minescent (EL) spectra in this kind of hybrid nanostructure-based LED exhibit ineffective energy transfer with respect to the photoluminescence. Therefore, PPFOH colloidal repre-cipitated nanoparticles with size of 80 nm (PL spectral with
CIE coordinates (0.30, 0.42)) were selected to fabricate the
WLEDs, in which nanoparticle thin ? lms were obtained via spin-coating from suspensions on the p -SiC (Figure S8). The current–voltage ( I –V ) curves in the hybrid WL EDs exhib-ited typical rectifying characteristics (Figure 3 b ). When the hybrid WLEDs was forward biased to about 15 V, the current reached up to 2.33 mA, while only a small reverse leakage current of 0.02 mA was observed at ?15 V. The hybrid WLEDs has turn-on voltage (current) of ca. 15 V (2.33 mA).
T he EL spectra of hybrid WL EDs based on the nanopar-ticles at various forward biased voltages are showed in Figure 3 c and no light emission was observed from the Macromol. Rapid Commun. 2014, 35, 895?900
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2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim F igure 3. a ) The device con? guration of the hybrid WLEDs based on PPFOH nanoparticles. b) Current–voltage ( I –V ) curve of the hybrid WLEDs; the inset is the enlarged current–voltage curve at the reverse bias. c) EL spectra at different voltages. d) CIE coordinates of hybrid WLEDs biased at various voltages.
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hybrid WLEDs under reverse bias. The EL spectra of hybrid WL EDs can be ? tted by three Gaussian curves with peak wavelengths at around 433, 474, and 535 nm that were
consistent with the PL pro? les (Figure 3 c ). The EL spectra showed lower emission intensities at long wavelength and
broad emission as compared with the PL spectra. For devices
based on PPFOH nanoparticles, EL spectra have the CIE chromaticity coordinates of (0.28, 0.32), (0.31, 0.34), (0.31, 0.32), and (0.35, 0.36) at 15, 20, 27.5, and 30 V, respectively. These values are well matched with the most optimized white light, with the CIE coordinates (0.33, 0.33) (Figure 3 d ). In addition, it should be noted that the EL spectra of PPFOH thin ? lm spin-coated from DMF solution for comparison exhibited only one emission peak at 560 nm under these experimental conditions. This supports the notion that nanoparticles are favorable for the white emission. 3.C onclusions W e have demonstrated state-of-the-art supramolecular conjugated polymer nanoparticles for application as WLEDs. In comparison with the controlled PPFO8 without hydroxyl group, hydrogen-bonded supramolecular conju-gated polymer PPFOH exhibited excellent supramolecular assembly behavior. PPFOH nanoparticles were obtained with size ranging from 40 to 200 nm via reprecipitation. PPFOH nanoparticles have fascinating size-dependent luminescent properties, affording a ? exible method to tune their emission color from blue–green, yellow to white. PPFOH nanoparticles with size of ca. 80 nm were observed to emit nearly white light with the CIE coordinates (0.30, 0.42). Prototype WL EDs using PPFOH nanoparticles with size of 80 nm exhibited white emission color with the CIE coordinates (0.31, 0.34) at 20 V. Supramolecular conjugated polymers are intriguing and versatile building blocks for self-assembly, and supramolecular polymer nanoparti-cles that will be promising organic nanoinks not only for WLEDs but also for organic nanodevices. S upporting Information S upporting Information is available from the Wiley Online Library or from the author. A cknowledgements: T he project was supported by the National Natural Science Funds for Excellent Young Scholar (21322402), the National Natural Science Foundation of China (21274064, 21144004, 61177029, 20974046), The Program for New Century Excellent Talents in University (NCET-11–0992), the Doctoral Fund of Ministry of Education of China (20133223110007), the Natural Science Foundation of Jiangsu Province (BK2011761, BK2008053, SJ209003), and the Program for Postgraduates Research Innovation in University of Jiangsu Province (CXLX11_0413, CXLX11_0423).[1]E .F.S chubert ,J .K.K im ,S cience 2005,308,1274.
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（1）表语从句 1．定义：用作表语的从句叫做表语从句。 2．构成：关联词+简单句 3．引导表语从句的关联词的种类： (1) 从属连词that。如： The trouble is that I have lost his address. 麻烦是我把他的地址丢了。 (2) 从属连词whether, as, as if。如： He looked just as he had looked ten years before. 他看起来还与十年前一样。 The question is whether they will be able to help us. 问题是他们是否能帮我们。 注：从属连词if一般不用来引导表语从句，但as if却可引导表语从句，如： All this was over twenty years ago, but it's as if it was only yesterday. gh能跟表语从句的谓语动词一般为系动词be, seem, look等。如： It looked as if it was going to rain. 看起来天要下雨了。 连接副词 where, when, how, why。 如：The problem is who we can get to replace her. 问题是我们能找到谁去替换她呢。 The question is how he did it. 问题是他是如何做此事的。 That was what she did this morning on reaching the attic. 那就是她今晨上了阁楼干的。 解释： 1．连词because可引导表语从句。如： I think it is because you are doing too much. 我想这是因为你做得太多。 2．在一些表示“建议、劝说、命令”的名词后面的表语从句中，谓语动词用虚拟语气。should+动词原形表示，should可省略。如： My suggestion is that we (should) start early tomorrow. 我的建议是我们明天一早就出发。（2）主语从句 1．定义：用作主语的从句叫做主语从句。 2．构成：关联词+简单句 3．引导主语从句的关联词有三类： (1) 从属连词that。如：That they were in truth sisters was clear from the facial resemblance between them. 很明显，她们确是亲姐妹，她们的脸型很相似。 (2) 从属连词whether。如： Whether he’ll come here isn’t clear. 他是否会来这里还不清楚。 (3) 连接代词who, whom, whose, what, which, whoever, whatever, whichever 连接副词 where, when, how, why。如： What she did is not yet known. 她干了什么尚不清楚。 How this happened is not clear to anyone. 这事怎样发生的，谁也不清楚。 Whoever comes is welcome. 不论谁来都欢迎。 Wherever you are is my home ---- my only home. 你所在的任何地方就是我的家----我唯一的家。 解释： 1．主语从句能用it作形式上的主语。常以it作形式主语的句型有： A. It+be+形容词(obvious, true, natural, surprising, good, wonderful, funny, possible, likely, certain, probable, etc.)+that从句。如： It is certain that she will do well in her exam. 毫无疑问她考试成绩会很好。 It is probable that he told her everything. 很可能他把一切都告诉她了。 B. It+be+名词词组(no wonder, an honour, a good thing, a pity, no surprise, etc.)+that
英语连词用法详解 一、单项选择连词 1．Owen wouldn’t eat anything ________ he cooked it himself. A．until B．since C．unless D．while 【答案】C 【解析】 句意：欧文不吃任何东西，除非这种东西是他自己亲自烹饪的。unless“除非”，符合语境。 2．_______ your opinions are worth considering, the committee finds it unwise to place too much importance on them. A．As B．Since C．Once D．While 【答案】D 【解析】While尽管，在本题中引导让步状语从句。尽管你的观点值得考虑，委员会发现过于重视它们是不明智的。 3．He was about to tell me the secret __ _____ someone patted him on the shoulder. A．as B．until C．while D．when 【答案】D 【解析】 试题分析：句意：她正要告诉我这个秘密，这时有人拍了一下她的肩膀。beabouttodo...when...是固定句型，意为“正要做……这时……”。 考点：考查连词。 【名师点睛】 用when引导时间状语从句的句型结构搭配 beabouttodosthwhen刚要,即将；正要做某事,突然发生其他事 bedoingsthwhen正在做某事突然 haddonesthwhen刚刚做过某事突然 beatthepointofdoingsthwhen就在做某事的关键时刻突然 scarcely...when/hardly...when几乎未来得及就…；刚一……就…… nosooner...than一……就…… 4．How long do you think it will be ________ the computer company brings out a new product? A．until B．when C．before D．that 【答案】C 【解析】分析句子，可知这是一个时间状语从句。根据句意，可知选C。 句意： 你认为在电脑公司发布一种新的产品之前，还需要经过多长的时间呢？
高中英语连词用法归纳 一、概说 连词是一种虚词，用于连接单词、短语、从句或句子，在句子中不单独用作句子成分。连词按其性质可分为并列连词和从属连词。并列连词用于连接并列的单词、短语、从句或句子，如and, but, or, for等；从属连词主要引出名词性从句(主语从句、宾语从句、表语从句等)和状语从句(时间状语从句、条件状语从句、目的状语从句等)，引出名词性从句的连词如that, whether等，引出状语从句的连词如when, because, since, if 等。 二、并列连词的用法 ◆ 1. 表示转折关系的并列连词。这类连词主要有but, yet 等。如： Someone borrowed my pen, but I don?t remember who. 有人借了我的钢笔，但我不记得是谁了。 He said he was our friend, yet he wouldn?t help us. 他说他是我们的朋友，但却不肯帮助我们。 ◆ 2. 表示因果关系的并列连词。这类连词主要有for, so 等。如： The child had a bad cough, so his mother took him to the doctor. 这孩子咳得很利害，所以他妈妈带他去看医生。 You are supposed to get rid of carelessness, for it often leads to serious errors. 你们一定要克服 粗枝大叶，因为粗枝大叶常常引起严重的错误。 注意：for表示结果通常不能放句首，也不能单独使用。 ◆ 3. 表示并列关系的并列连词。这类连词主要有and , or , either…or , neither…nor , not only…but(also) , both…and , as well as 等。如： He didn?t go and she didn?t go either. 他没去，她也没去。 The weather is mild today; it is neither hot nor cold. 今天天气很温暖，不冷也不热。 Both New York and London have traffic problems. 纽约和伦敦都存在交通问题。 It is important for you as well as for me. 这对你和对我都很重要。 People who are either under age or over age may not join the army. 年龄不到或者超龄的人都不得参军。 三、从属连词的用法 ◆1. 引导时间状语从句的从属连词 (1) 表示“当…时候”或“每当”的时间连词。主要的when, while, as, whenever。如： Don?t talk while you?re eating. 吃饭时不要说话。 Vegetables are best when they are fresh. 蔬菜新鲜时最好吃。 He came just as I was leaving. 我正要走时他来了。 (2) 表示“在…之前(或之后)”的时间连词。主要的有before, after。如： Try to finish your work before you leave. 离开前设法把工作做完。 After we have finished tea, we will sit on the grass. 喝完茶之后我们将坐在草地上。 (3) 表示“自从”或“直到”的时间连词。主要的有since, until, till。如： She?s been playing tennis since she was eight. 她从八岁起就打网球了。 Hold on until I fetch help. 坚持一下，等我找人来帮忙。 Never trouble trouble till trouble troubles you. (谚)不要无事惹事。 (4) 表示“一…就”的时间连词。主要的有as soon as, the moment, the minute, the second, the i nstant, immediately, directly, instantly, once, no sooner…than, hardly…when等。如： I?ll let you know as soon as I hear from her. 我一接她的信就通知你。 The moment I have finished I?ll give you a call. 我一干完就给你打电话。 I came immediately I heard the news. 我一听到这个消息，马上就来了。 Once you begin you must continue. 你一旦开始, 便不可停下来。 (5) 表示“上次”、“下次”、“每次”等的时间连词。主要的有every time(每次)，each time(每次)，(the) next time(下次)，any time(随时)，(the) last time(上次)，the first time(第一次)。如： I?ll tell him about it (the) next time I see him. 我下一次见到他时，我就把这个情况告诉他。We lose a few skin cells every time we wash our hands. 每当我们洗手的时候，我们都要损失一
高中英语语法——连词 1.定义：连词是一种虚词，用于连接单词、短语、从句或句子的词。 2.连词在句子中不单独用作句子成分。 3.分类：连词按其性质可分为并列连词和从属连词。
连词造句练习： 1.上完最后一节课之后，我就回家了。 2.你和他都是我的朋友。 3.她不但喜欢唱歌，还喜欢画画儿。 4.——我不喜欢吃芒果。 ——我也不喜欢。 5.就篮球而言，我比他打得好一点儿。 6.除非他先向我道歉，否则我不会原谅他的。 7.直到他离开了我，我才意识到他很重要。 8.虽然我不喜欢吃香蕉，但我也不讨厌它。
七选五练习 （一） When I was in high school and college, I went to fast food restaurants pretty often. Even until today, fast food is a popular choice among students. So, what makes fast food restaurants really popular year after year? The food is not very expensive. 1 So, it is good to get something tasty to eat and still have some money left for a movie later. Nowadays, many fast food restaurants open till late nights. 2 Most teenagers go there also because other boys and girls are there. It is fun to be there, as seen in fast food TV advertisements. It is cool. 3 You can just order fries or you can also mix and match with plenty of choices, such as coke with French fries, sundae with apple pies, salad with burgers. And managers there will not stare at you for reading there for hours if you just order French fries and a cup of coke. 4 They can have group discussions of school projects, small talk and even birthday celebrations. You can try telling them some fast food is unhealthy, but I doubt if youngsters will listen. 5 Some of them go to a fast restaurant every week. The food there is cheap, delicious, and served fast. A. Fast food does not have to be bad for you. B. Many teenagers do not have much money. C. Fast food is still popular with many of them. D. At fast food restaurants, you choose what you want. E. Today, fast food restaurants are offering healthier food. F. A fast food restaurant is a good place for some activities for teenagers. G. So, these places are comfortable and safe to hang out during late nights. Key: A B D F G My friend Jerry was one of the most positive people I had ever known. 1 If his employee had a bad day, Jerry always helped him to look on the positive side of the situation. 2 So one day I asked him, “ How can you be so positive all the time?” He replied,
高考英语连词经典习题(含答案) 一、单项选择连词 1． Tina was hesitation about the job offer as she did not know _______ the company was an established one. A．whether B．what C．until D．although 【答案】A 【解析】 2．To live in honor, he came from a poor family, was his ambition. A．though B．if C．unless D．however 【答案】A 【解析】though尽管if如果;是否unless除非however无论怎样,根据题意他的野心就是为了有尊严的活着,尽管他来自一个贫穷的家庭.故选A. 3．I’m sorry I got caught in the traffic；_________, I could have been here sooner．A．besides B．although C．anyway D．otherwise 【答案】D 【解析】考查含蓄虚拟条件句。I could have been here sooner是和过去事实相反的虚拟语气，四个选项中只有otherwise可以充当含蓄虚拟条件，相当于if I had not got caught in the traffic.所以选D。 4．The photo brought me back to the memory of the time in Qingdao, _____ I spent my summer holiday by the seaside with my friends. A．that B．when C．which D．what 【答案】B 【解析】 考查定语从句。先行词是the time，在定从_____ I spent my summer holiday by the seaside with my friends.中作时间状语。所以选B。 5．_____ astronauts cannot go to a baseball game or a movie in space, there are many familiar activities that they can still enjoy. A．Once B．Unless C．While D．Since 【答案】C 【解析】 while在此句中作为连词，表让步，意思是“虽然，尽管”。 句意： 在太空中，宇航员们虽然不能去看棒球比赛或看电影，但那里还有很多相类似的活动他们
英语语法大全:连词 连词（Conjuction—conj.） 定义用以连接句子中的单词、短语、从句，或连接句子和句子的词叫做连词。例如： and（和），but（但是），so（所以），or（或者），… that，because（因为），since（既然），… 连词的表达功能如下： （1）并列功能（“+”代表连词） （a）词+词 boys and girls（男生和女生） you and I（你和我） poor but happy（贫困的，但是快乐） （b）短语+短语 in the city and in the country.（在城市和在乡村） by bus or by train（乘公共汽车或乘火车） （c）从句+从句 例：He is not very bright but he studies hard. （他并不聪敏，但是他很用功。） 例：I didn't have breakfast this morning, so I am hungry now. （今天早晨我没吃早餐，所以我现在饿了。）解说表达并列功能的连词叫做并列连词（Coordinate Conjunction）。并列连词两端的词的词类必须相等。又如“词+短语/从句”或“短语+词/从句”等也都不成立。 （2）从属功能 请先了解什么叫做从句（Subordinate Clause.）
本身不能独立表达完整的意思而只在句子中作句子结构的一部分者叫做从句。用以连接从句使其在主句中发挥表达功能的词叫做从属连词（Subordinate Conjunction）。 as，when，since，that，who，which，what，… 例：I know that he is a very good student. （我知道他是一个很好的学生。—“that…”是名词从句作“know”的直接宾语。） 例：People who use free time well are usually healthy and happy. （善于利用空闲时间的人通常都是又健康又快乐。—“who…well”是形容词从句修饰其前面的名词“People”。） 例：Many people enjoy reading when they have free time. （许多人有空闲就喜爱阅读。—“when…time”是副词从句在修饰动词“enjoy”。）
英语连词用法总结(完整) 一、单项选择连词 1．Read this story, you will realize that not everything can be bought with money. A．or B．and C．but D．so 【答案】B 【解析】 试题分析：考查并列句。句意看看这个故事，你就会明白不是所有的东西都可以用钱买到的。“祈使句 + and/or +陈述句”是一个固定句式，根据句意，选B 考点 : 考查并列句。 2．——Have you got the results of the final exam? ——Not yet. I'm afraid it will be a few days we know the final results. A．before B．after C．until D．when 【答案】A 【解析】考查连词的用法。根据句意：你知道期末考试的结果了吗？还不知道呢，恐怕再过一些天我们才知道最终的结果。before …才…，after …之后，until直到，when当什么时候，故选A。 3．We shouldn’t think the question of ________ they are poor or rich is important. A．what B．whether C．why D．how 【答案】B 【解析】考查考查名词性从句。句意“我们不应该把他们是穷人还是富人看得太重要。”whether常与or/or not连用，意为“是否......”。故选B。 4．— How can I wake up so early? — Set the ala rm at 5 o’clock,you’ll make it. A．but B．or C．and D．so 【答案】C 【解析】 试题分析：考查情景交际和并列连词。句意：--我怎样才能醒的很早？--把闹钟定到5点，这样，你就能做到了。答语前后是并列关系，祈使句+and表示条件，相当于if条件句。or 表示相反的情况，故选C。 考点：考查情景交际和并列连词 5．He was about to tell me the secret __ _____ someone patted him on the shoulder. A．as B．until C．while D．when
四种名词性从句(宾语从句、主语从句、同位语从句、表语从句)讲解与练习 ◆学习宾语从句 学习宾语从句的连词、语序、时态和各种变化及特殊用法(直接引证变间接引语也在 宾语从句的基础上还要进行人称、状语、少数动词和句型的变化)是为学习其它三种名词性从句(主从、表从、同位从)做铺垫，连词、语序、时态基本相同，只是后三种考点相对宾.语从句少的多，主要是对连词的应用进行考查。所以学好宾语从句是必要的。 宾语从句三注意三特殊 一注意:注意引导词(连词) 由陈述句转化而来的宾语从句，引导词为that，that 在口语或非正式文体中可省略;由 一般疑问句转化而来的宾语从句，引导词为if或whether;由特殊疑问句转化而来的宾语从句，引导词为句子本身的特殊疑问词，即what, when，where 等。 Eg：Tom says(that)he will fly to Beijing tomorrow. 汤姆说他明天将要坐飞机去北京 二注意:注意从句语序. 宾语从句的语序应该为陈述句语序即“主语+谓语+宾语+其他”。也就是说将疑问句转化成宾语从句时，一定要将疑问句语序转变成陈述句语序。 Can you tell me what he is doing能告诉我他正在做什么吗? <特别提醒>当疑问句在宾语从句中做主语时，语序不变。 Eg：Do you know what makes him so angry? 你知道什么事使他如此生气吗？ <特别提醒>如果宾语从句表示的是客观真理或是科学事实，其谓语动词仍用一般现在.时态。 Eg：Our teacher told us that the sun is much bigger than the moon. 老师告诉我们说太阳比月球大得多。 ◆主语从句(与宾词从句连词、语序、时态相同。只是不能用if, that 不可省;) (一)、主语从句是一个句子，在句子中作主语成分。 (二)，主语从句的特点 1.与宾语从句使用同样的连接词，只是if不能用; 1)、陈述句用that。 2)、一般疑问句用whether。 3)、特殊疑问句用特殊疑问词what, which, who,when, where, why, how等词引导。 2.以it为形式主语出现 Eg：1.It's true that the earth is round. That the earth is round is true. 2.表是否的意思时，不能用if代替whether. It hasn't been decided whether he'll come or not. Whether he'll come or not hasn't been decided. 3.从句语序为主谓宾正常语序。 Why didn't he come? Why he didn't come is not known. （三）特殊疑问词变化 Whoever=no matter who=any one who Whomever=no matter who=any one who
高中英语语法连词 一.概念 连词是用来连接词,短语,从句或句子的词.连词不作成分. 二.相关知识点精讲 1.表示并列关系的连词有：and, both…and…,not only… but also…和neither…nor…等 1)and：和，并且 A：基本用法： “and”表示“和”、“并且”的意思，用来连接对等关系的字和字，片语和片语，句子和句子。 I enjoy basketball , football and table tennis. The weather becomes colder and colder. B:特别用法： 祁使句后连接and，有条件句作用，此时and=if you…,you’ll… Go straight on, and you’ll see the library.==If you go straight on, you will see the library. 2)both…and…既…也…,(两者)都… A、both…and…构成的词组作主语时,谓语动词用复数。 Both Jim and Kate are from England. B、both…and…否定句表示部分否定。 You can’t speak both German and English. Both my father and my mother aren’t doctors. 3)neither…nor…:既不…也不… neither…nor…连接两个并列主语时,谓语动词靠近哪个主语就与哪个主语保持“人称”和“数”的一致，即采取就近原则。 Neither I nor he has seen the play before. 4)not only…but also…:不但…而且… no t only…but also…连接两个主语后的谓语动词也遵循就近原则。 Not only the mother but also the children are ill. 2.表示转折关系的连词有：but, however, yet, still，while等。 Mary was a nice girl, but she had one shortcoming. Tom got up early, yet he failed to catch the train. He was very tired, still he kept on walking. Your composition is fairly good, however, there is still some room for improvement. Jane is hard working ,while her sister is quite lazy. 3.表示选择关系的并列连词有：or, either…or…,whether… or…等。 1)or：或、否则 A:基本用法 or 表示“或” 的意思，使用于两者之中选择一个的时候。 ----Is your friend English or American? ----American. He doesn’t like dumplings or noodles. B:特别用法 祁使句后连接or ，表“如果…,否则…”,有转折的意思，此时or =if you
连词详解+例句 一、单项选择连词 1．I was glad to meet Jenny again, _______ I didn’t want to spend all day with her． A．but B．and C．so D．or 【答案】A 【解析】 本题考查连词。句意：我很高兴再次见到Jenny，但是我不想整天都和她呆在一起。but：但是，表示转折关系；and：并且，表示并列关系；so：所以，表示因果关系；or：或者，否则，表示选择关系。选A。 考点：连词／连接词 2．_____ astronauts cannot go to a baseball game or a movie in space, there are many familiar activities that they can still enjoy. A．Once B．Unless C．While D．Since 【答案】C 【解析】 while在此句中作为连词，表让步，意思是“虽然，尽管”。 句意： 在太空中，宇航员们虽然不能去看棒球比赛或看电影，但那里还有很多相类似的活动他们仍然是可以玩的。 考点：连词／连接词 3．Life isn’t always beautiful, ________ the struggles make you stronger and the changes make you wiser. A．or B．so C．but D．for 【答案】C 【解析】 试题分析：考查连词。句意：生活不总是美丽的，但是困难使你更强壮，改变使你更明智。or或者，否则；so所以，因此；but但是；for因为。故选C。 考点：考查连词 4．Lily’s drawing may not be excellent, ______ I know she has done her best. A．so B．although C．before D．as 【答案】D 【解析】考查连词。句意：莉莉的绘画可能不是优秀的，因为我知道她已经尽力了。此处用as引导原因状语从句，故答案为D。 5．_______houses are getting more and more expensive, people want to buy one of their own.
16 连词 连词分为并列连词和从属连词两大类。并列连词是连接主语与主语，谓语与谓语，句子与句子，分词与分词的词，它要求前后两部分有相同的形式和语法作用；而从属连词一般连接主句与从句，从句形式有名词性从句，定语从句和状语从句等。 （一）并列连词： 并列连词可用来连接词与词，词组与词组，分句与分句。常用的并列连词有：and （和），as well as（既…又），both … and（不但…而且），not only … but also（不但…而且），not … but（不是…而是），neither … nor（既不…也不），either … or（不是…就是），or（或者），but （但是），yet（然而），for（因为），so（所以），while（而），when （这时）等。如：Both my brother and my sister are teachers./ His room is bright but mine is gloomy（暗沉沉的）./ He can not only repair radios but also fix them./ It is a glorious（光荣的）yet difficult task./ Strike while iron is hot. （二）从属连词 从属连词是指在复合句中引导从句的连结词。常见的从属连词有： 引导时间状语从句的：after, before, when, as, while, since, until, till, as soon as 引导原因状语从句的：because, since, as 引导让步状语从句的：although, though, no matter（无论）, even if (though) 引导条件状语从句的：if, unless, once, so (as) long as 引导结果状语从句的：so … that …, such … that … 引导目的状语从句的：so that …, in order that … 引导比较状语从句的：as … as …, not so (as) … as …, … than … 引导方式状语从句的：as if … 引导主语，宾语或表语从句的连词主要有：that, whether, if三个。其中that 和whether间或还可以引起同位从句和状语从句。 （三）某些用法比较特殊的从属连词用法区别 1、当while, when, as引导时间状语从句时的区别：①while引导的状语从句中动词必须是持续性。谓语动词多为进行时，或状态动词的一般时。while 的这些用法可用when代替，等于 "at the time that", "during the time that"。例如：Please keep quiet while (when) others are studying；② when除可指一段时间外，还可用来指一点时间，等于 "at the time"，也就是说when引出的时间状语从句中的谓语动词可以是终止性的，也可以延续性的。因此主句和从句的谓语可以是一般时，进行时，或完成时。例如：When I went into the lab, the teacher was doing an experiment.（when不能换成while）He often makes mistakes when he is speaking English.（when可换成while）③as常可与when，while通用，但强调"一边、一边"。例如：As (when, while) I was walking down the street, I noticed a police car in front of number 37. ④when引导的状语从句中的主语与主句主语一致，主、谓是"主语系动词"结构时，这时主语和系动词可以省略。例如：When (he was) young, he worked for a rich man./ She'll be here to give you help when (if it is) necessary. ⑤when有时代替if，引导条件句，意为"如果"、"假如"，例如：I'll come when (if) I'm free. 2、before作连词一般表示时间，意为"在…之前"，但有些句子中这样译就显得别扭。试看以下句子的翻译：He almost knocked me down before he saw me.他几乎把我撞倒才看见我；Before I could get in a word he had measured me.我还没来得及插话，
最新英语连词用法总结(完整) 一、单项选择连词 1．Read this story, you will realize that not everything can be bought with money. A．or B．and C．but D．so 【答案】B 【解析】 试题分析：考查并列句。句意看看这个故事，你就会明白不是所有的东西都可以用钱买到的。“祈使句 + and/or +陈述句”是一个固定句式，根据句意，选B 考点 : 考查并列句。 2．To live in honor, he came from a poor family, was his ambition. A．though B．if C．unless D．however 【答案】A 【解析】though尽管if如果;是否unless除非however无论怎样,根据题意他的野心就是为了有尊严的活着,尽管他来自一个贫穷的家庭.故选A. 3．He was about to tell me the secret __ _____ someone patted him on the shoulder. A．as B．until C．while D．when 【答案】D 【解析】 试题分析：句意：她正要告诉我这个秘密，这时有人拍了一下她的肩膀。beabouttodo...when...是固定句型，意为“正要做……这时……”。 考点：考查连词。 【名师点睛】 用when引导时间状语从句的句型结构搭配 beabouttodosthwhen刚要,即将；正要做某事,突然发生其他事 bedoingsthwhen正在做某事突然 haddonesthwhen刚刚做过某事突然 beatthepointofdoingsthwhen就在做某事的关键时刻突然 scarcely...when/hardly...when几乎未来得及就…；刚一……就…… nosooner...than一……就…… 4．I’m sorry I got caught in the traffic；_________, I could have been here sooner．A．besides B．although C．anyway D．otherwise 【答案】D 【解析】考查含蓄虚拟条件句。I could have been here sooner是和过去事实相反的虚拟语
高中英语语法练习介词和连词（5） 1.The doctor will be free _______. A. 10 minutes later B. after 10 minutes C. in 10 minutes D. 10 minutes after 2.Did you have trouble ______the post office ? A. to have found B. with finding C. to find D. in finding 3.We offered him our congratulations ______ his passing the college entrance exams. A. at B. on C. for D. of 4.If you keep on , you ’ll succeed _______. A. in time B. at one time C. at the same time D. on time 5. —How long has this bookshop been in business? —______1982. A. After B. In C. Form D. Since 5.The train leaves at 6:00 pm. So I have to be at the station ______5:40 pm. at the latest. A. until B. after C. by D. around 7.Your performance in the driving test didn’t reach the required standard; _______, you failed. A. in the end B. after all C. in other words D. at the same time 8.I don’t think I’ll need any money but I’ll bring some _______. A. at last B. in case C. once again D. in time 9.______production up by 60%, the company has had another excellent year. A. As B. For C. With D. Through 10.Faced ______serious flooding , the victims got aid from all parts of the country. A. with B. by C. to D. about 11.It took them long to be accustomed ______the local food and customs. A. to B. of C. in D. for https://www.doczj.com/doc/2417790170.html,e and see me ______two or three _______. A. for…days B. after…days C. in…days’ time D. during…day time 13.For miles around me there was nothing but a desert , without a single plant or tree ______. A. in sight B. on earth C. at a distance D. in place 14.I wanted two seats ______Madame Curie for Friday night , so I rang the cinema to see if I could book two tickets. A. of B. about C. to D. for 15.______ most students, she was always well prepared and never came to class late. A. Like B. As C. For D. To 16.Washington , a state in the US, was named _____one of the greatest American presidents. A. in honor of B. instead of C. in favor of D. by means of 17.The number of the employees has grown from 1,000 to 1,200 . This means it has risen ______20 percent . A. by B. at C. to D. with 18.The suit fitted him well ______the color was a little brighter. A. expect for B. except that C. except when D. besides 19.—You seem to show interest in cooking . —What ? ______, I’m getting tired of it . A. On the contrary B. To the contrary C. On the other hand D. To the other hand 20.The lady is not in the mood ______going on a sightseeing trip. A. of B. for C. in D. to 21.Beijing is an ancient capital ________ a history of 3000 years. A. on B. of C. for D. with 22.We need fifteen more people ______our team to do the job.