5. all 和 both 的用法。
1）all 指三者以上，或不可数的东西。谓语动词既可以用单数，也可以用作复数。在句中作主语、表语、宾语、同位语和定语。
All of us like Mr Pope. 我们都喜欢 Pope 先生。（作主语）
= We all like Mr Pope. ( 作同位语 )
All the water has been used up. ( 作主语 )
That's all for today. ( 作表语 )
Why not eat all (of) the fish? ( 作宾语 )
All the leaders are here. ( 作定语 )
2）both 作代词。
①与其他名词或代词并列出现，表示 “ 两个都 ” 。
Lucy and Lily both agree with us.
They both passed on their sticks at the same time.
How are your parents? They're both fine.
②与“ of + 代词（或名词）”连用，表示“两者都”。
Both of them came to see Mary.
Both of the books are very interesting.
③单独使用，表示“两者（都）”。
Michael has two sons. Both are clever.
I don't know which book is the better, I shall read both.
3）both 用作形容词，放在名词之前，修饰该名词，表示“两者都”。
Both his younger sisters are our classmates.
There are tall trees on both sides of the street.