Chapter 5 Semantics 语义学
1. What is semantics？什么是语义学？
Semantics can be simply defined as the study of meaning in language.
语义学可定义为对语言意义的研究。
2. Some views concerning the study of meaning
语义研究的几种主要理论
1) The naming theory 命名论
It was proposed by the ancient Greek scholar Plato. According to this theory, the linguistic forms
or symbols, in other words, the words used in a language are taken to be labels of the objects they
stand for. So words are just names or labels for things.
命名论是最原始的语义理论，是古希腊学者柏拉图提出的。该理论把词看作是该词所指事物的名称或标记。
2) The conceptualist view 意念论
The conceptualist view holds that there is no direct link between a linguistic form and what it
refers to; rather, in the interpretation of meaning they are linked through the mediation of concepts
in the mind.
意念论认为，语言形式及其所代表的对象之间（即语言与现实世界之间）没有直接联系；确切地说，在理解语义时，是通过大脑中存在意念这一中介物来联系的。
83 Chapter 5: Personnel Planning and Recruiting
1. ________ is the process of deciding what positions the firm will have to
fill. Personnel planning
2. Jane must decide what positions the firm should fill in the next six months.
What activity is Jane working on? personnel planning
3. When a company decides on how to fill top executive positions, the
process is called ________. succession planning
4. When planning for employment requirements, what must be forecasted?
a. personnel needs
b. supply of inside candidates
c. supply of outside candidates
5. Which term below means studying variations in a firm’s employment
levels over time?trend analysis
6. Trend analysis is limited in its usefulness, because ________.
it considers time but not other changes such as productivity
7. The process of making forecasts based on the ration between some causal
第五章 不可压缩流体的二维流动
引言：在前面几章主要讨论了理想流体和黏性流体一维流动，为解决工程
实际中存在的一维流动问题打下了良好的基础。本章讨论理想不可压流体的二维有势流动以及二维黏性流体绕物体流动的基本概念。
第一节 有旋流动和无旋流动
刚体的运动可分解为移动和转动两种运动形式，
流体具有移动和转动两种运动形式。另外，由于流体具有流动性，它还具有与刚体不同的另外一种运动形式，即变形运动(deformationmotion)。本节只介绍流体旋转运动即有旋流动(rotation — alflow) 和无旋流动(irrotational
flow)。
一、有旋流动和无旋流动的定义
流体的流动是有旋还是无旋，是由流体微团本身是否旋转来决定的。流体在流动中，如果流场中有若干处流体微团具有绕通过其自身轴线的旋转运动， 则称为有旋流动，如果在整个流场中各处的流体微团均不绕自身轴线的旋转运动，则称为无旋流动。
强调“判断流体流动是有旋流动还是无旋流动，仅仅由流体微团本身是否绕自身轴线的旋转运动来决定，而与流体微团的运动轨迹无关。”
举例虽然流体微团运动轨迹是圆形，但由于微团本身不旋转，故它是无旋流动；在图 5—1(b)中，虽然流体微团运动轨迹是直线，但微团绕自身轴线旋转，故它是有旋流动。在日常生活中也有类似的例子，例如儿童玩的活动转椅，当转轮绕水平轴旋转时，每个儿童坐的椅子都绕水平轴作圆周运动， 但是每个儿童始终是头向上，脸朝着一个方向，即儿童对地来说没有旋转。二、旋转角速度(rotationalangularvelocity)
为了简化讨论，先分析流体微团的平面运动。如图 5—2 所示有一矩形流体微团 ABCD 在 XOY 平面内，经丛时间后沿一条流线运动到另一位置，微团变形成 A，B，C，D。
流体微团在 Z 周的旋转角速度定义为流体微团在 XOY 平面上的旋转角速度
的平均值
同理可求得流体微团旋转角速度的三个分量为
Chapter 5 Syntax 句法
I. Multiple Choices:
1.D. Immediate Constituent 2. B. semantic 3. A. concord
4. A. the future is not expressed by morphological change
5. D. substitutability 6. C. co-occurrence
7. B. Predicate 8.B. syntactic 9. C. self-control
10. D. Government 11. D. coordinate
II. Fill in the blanks with the most suitable words:
1. Cohesion refers to ties and connections which exist within texts. They are also
called formal links between sentences and between clauses.
2. A sentence structure that is made up of layers of word groups is called a
hierarchical structure.
3. Sentences are traditionally assumed to be made up of words in _linear___ direction.
4. Provide linguistic terms for the following descriptions.
1) a type of relation holding
between elements replaceable with each other at a
