7.4 It's for sb.和 It's of sb.

1）for sb. 常用于表示事物的特征特点，表示客观形式的形容词，如easy, hard, difficult,　 interesting, impossible等：

　　 It's very hard for him to study two languages. 对他来说学两门外语是很难的。

2）of sb的句型一般用表示人物的性格，品德，表示主观感情或态度的形容词，如good, kind, nice, clever, foolish, right。

　　 It's very nice of you to help me. 你来帮助我，你真是太好了。

　

for 与of 的辨别方法：

　　用介词后面的代词作主语，用介词前边的形容词作表语，造个句子。如果道理上通顺用of，不通则用for。如：

　　 You are nice.　(通顺，所以应用of)。

　　 He is hard.　(人是困难的，不通，因此应用for。)

7.5 不定式作表语

　不定式可放在be动词后面，形成表语。例如：

　　 My work is to clean the room every day.

　　 His dream is to be a doctor.

7.6 不定式作定语



　 不定式做定语通常要放在被修饰的词后。例如：

I have a lot of work to do.　

So he made some candles to give light.

7.7 不定式作状语

1）目的状语　

To… only to (仅仅为了),　in order to,　so as to,　so(such)… as to… (如此……以便……)

　　He ran so fast as to catch the first bus.　他飞快地跑以便赶上第一班车。

　　I come here only to say good-bye to you.　我来仅仅是向你告别。

2）作结果状语，表事先没有预料到的，要放在句子后面。

　　What have I said to make you angry.

　　He searched the room only to find nothing.

3)　表原因

　　I'm glad to see you.

典型例题

　The chair looks rather hard, but in fact it is very comfortable to ___.　

　A. sit　 B. sit on　 C. be seat　 D. be sat on

答案：B.　如果不定式为不及物动词，其后应有必要的介词。当动词与介词连用时，常位于"形容词+动词不定式"结构的末尾。