五种基本句型——主系表结构
主（语）＋系（动词）＋表（语）
主语，主语是五种基本句型都具备的。
从位置上来看，主语一般在句子开头，也就是一个句子的“头把交椅”。
从意义上理解，主语一般是一个句子的“陈述对象”，后面的一切都是针对主语来说的。
主语一般是名词或代词（当然还有其他，这里暂且详细讨论）
系动词是联系动词的简称，顾名思义，它是起到联系作用的动词，是连接主语和表语的。系动词的数量是有限的，常见的只有十来个，我们把它们分成四组，这样有助于我们记忆系动词：
一、be动词类：am、is 、are 、was 、were
二、表示变化类：become、get 、turn 、grow 、go
三、感官动词类: 眼（look ）耳(sound)鼻(smell)舌(taste)身(feel)
四、表示延续性的动词：remain 、stay 、keep
表语
从位置上来讲，它总是在系动词后面（系动词和表语关系甚为紧密，没有系动词，就没有表语：没有表语，就没有系动词。
二从意义上讲，表语通常是来说明主语的性质、特征的。表语通常是由形容词、介词短语、名词、代词、动词不定式、doing 等来充当。
上面就是对主系表结构的简要介绍，其中，系动词是主系表结构的核心，它是这个结构的标志，看到了系动词，也就能立刻判断出句子的结构是主系表，因此，
记住系动词非常重要。
练习
找出下面句子中的主语、系动词及表语，并指出主语和表语分别是由什么词性或词类来充当的。
1 Tom is a student.
2 He is fat.
3 I am tired .
4 We are students.
5 The bag was lost .
6 The boy was foolish .
7 They were kind.
8 She is in the room.
9 The books are on the desk.
10 Snow is white.
11 Kate was here yesterday.
12 My father became a teacher in 1978.
13 The weather gets hot in summer.
14 She looks beautiful.
15 The flower smells good.
16 We were very happy.
17 You are right.
18 The soup tastes delicious.
19 The chair is yours.
20 The children are asleep.
21 The story is interesting.
22 He feels better today.
23 The leaf turns green.
24 I stayed awake all the night.
25 The weather still remained cold in April.
26 The little girl is six.
27 My work is to look after the baby.
28 His job is taking care of the patient.
29 The girl is very pretty.
30 He went mad.
31 Please don’t get angry.
32 The weather is getting colder and colder.
33 You look angry.
34 She looks like her mother.
35 You look unhappy, what’s the matter?
36 Those roses smell beautiful.
37 This tastes nice. What’s in it?
38 Do you feel happy?
39 He remained silent.
40 The weather is going to stay fine.
41 M y job is teaching English．
42 She is at home．
43 I feel terrible．
44 He is older than he looks．他比看上去要老。
45 He seen interested in the book．他似乎对这本书感兴趣。
46 The story sounds interesting．这个故事听起来有趣。
47 The desk feels hard．书桌摸起来很硬。
48 The cake tastes nice．饼尝起来很香。
49 The flowers smell sweet and nice．花闻起来香甜。
50 You have grown taller than before．你长得比以前高了。
51 He has suddenly fallen ill．他突然病倒了。
52 He stood quite still．他静静地站看。
53 He becomes a teacher .．他当了教师。
54 He looks well.他面色好。
55 It sounds nice.这个听起来不错。
56 I feel good.我感觉好。
