101.such as 和for example
这两个短语都可以作“例如”解。for example用来举例说明某一论点或情况，一般只举同类人或物中的“一个”为例，作插入语，可位于句首，句中或句末。例如：
Ball games, for example, have spread around the world. 球类运动就已经在世界各地传播开了。
What would you do if you met a wild animal？？a lion, for example? 如果遇上野兽，例如狮子，你该怎么办？
such as用来列举事物时，一般列举同类人或事物中的几个例子。插在被列举的事物与前面的名词之间，as后面不可有逗号。例如：
Some of the rubbish, such as food, paper and iron, rots away over a long period of time.
有些废物，如剩饭、废纸和废铁，时间一久就烂掉了。
注意：使用这个短语时，后面列举的事物的数量不能等于它前面所提到的总和，一旦相等就要用that is或namely。如不可以说：I have three good friends, such as John, Jack and Tom. 应该说：I have three good friends, that is, John, Jack and Tom。我有三个好朋友，即约翰、杰克和汤姆。
102.reason 和cause
The ____ of the big fire was his carelessness.
A.reason B.cause C.causing D.reasoning
解答：B。reason强调一种推理的理由，而cause是指导致某件事情发生的人或事。
103.when while 与 as
1,when表示“当……的时候”。从句中既可用延续性动词，又可用非延续性动词，这些动词既可以表示动作，又可表示状态。从句中的动作既可和主句的动作同时发生，又可在主句的动作之前或之后发生。如：
When I came into the room, I found him lying there asleep.
Mary was having dinner when I saw her.
When you meet a word you don''t know, consult the dictionary.
She was beautiful when she was a girl.
如果when从句的主语与主句主语相同，谓语又是be动词，从句主语和be可以省略：当when从句主语与主句主语相同时，用when加分词可以替代状语从句。如：
When（you are）in trouble, ask her for help.
When（I was）sleeping, I never heard a thing.
2，as
(1)表示"当……时"、"和……同时"。常指从句的动作未结束，主句中的动作就已发生。从句中多用表示动作的动词，而不用be动词或表示感觉、理解、知道这类动词。
As he stood there, he saw two men enter the bar.
She dropped the glass as she stood up.
As I was walking down the street, an American asked me for directions to the nearest station.
(2)用于平行的动作中，表示"一面……一面……"。常指一个主语同时进行两个动作。如：
He sang as he worked.
The students took notes as they listened.
3,While表示"在……的时候"、"在……期间"。它强调主句的动作与从句的动作同时发生或主句的动作发生在从句的动作过程中。While从句中必须是表示动作或状态的延续性动词。如：
Never get on or off a bus while it is in motion.
The weather was fine while we were in Beijing.
She called while I was out.
104.become,get和turn
get，turn，become等均可译为“变得”，但它们在用法上有些区别。
（1）get用于日语，通常跟随比较级。
It gets coldr。天气变冷了。
（2）turn是指在颜色和性质等方面变得与原来不同。
His face truned red。他的脸变红了。
（3）become是指身份、职位的变化，作瞬间动词时指状态的变化。
He becomes a teacher 。他成了一名老师。
将来“成为”不用“become”而用"be"。
She will be a teacher。她将成为一名老师。
105.near 与 beside
near,by,beside表示“在……附近”的区别：
near表示相对的“近”， 实际距离可能还很远。例如：
Suzhou is near Shanghai.
There is a post office near our school.
beside表示“靠近”，实际距离不可能很远，例如：
He was sitting beside her.