1．for example, for instance, such as, like

（1）for example用来举例说明。为句中插入语，其前后需用逗号隔开。它可用于句首、句中或句末。

Fox example, liquid has no definite shape.

例如，液体没有固定的形状。

Noise, for example, is a kind of pollution.

例如，噪音是一种污染。

Many great men have risen from poverty-Lincoln and Edison, for example.

许多伟人是从贫困中崛起的-比如林肯和爱迪生。

（2）such as用来列举同类人或事物中的几个例子。such as后切不可用逗号，

　　如：

Some of the European languages come from Latin, such as French, Italian and Spanish.

有些欧洲语言来源于拉丁语，例如法语、意大利语和西班牙语。

Note: 使用such as来举例子，只能举其中一部分，不能全部举出。若全部举出，要改用namely或者that is to say(意为：即)。

如：

He knows four languages, namely(=that is to say) Chinese, English, Russian and French.

他精通四门语言，即汉语、英语、俄语和法语。

（3）like也常用来举例，可与such as互换。

　　如：

Some cold-blooded animals, like(=such as) the cat, the dog or the wolf, do not need to hibernate.

such as 用于举例时可以分开使用，这是不能与like互换。

Such people as you described just now are very common these days.

像你刚才描述的那种人这些日子很常见。

（4）for instance经常与for example互换。

　　如：

There are occupations (which are) more dangerous than truck driving; for instance (for example), training tigers. 比开卡车危险的职业还是有的，比如说驯老虎。

2．opportunity ，occasion与chance的区别：