2.1）单项选择

（1）We'll _________ finish the job,however long it takes.

A.ought to B.must

C.have to D.should

答案:C

（2）Do you know the difficulty he had _________ the work?

A.on finishing B.to finish

C.finishing D.having finished

提示:题中he had...the work是定语从句，修饰difficulty。have difficulty(in) doing sth.是固定句型。关系代词that被省略，in也被省略，故出现had与finishing相邻的情况。此题易误选B。

答案:C

2)完成句子

I _________ _________ _________ _________my notebooks for the exam.

为了考试我必须把笔记复习一遍。

答案:have to look through

3.need表示"需要"，主要用于否定句和疑问句

用于疑问句，肯定回答用must，否定回答用needn't。have to表示他人或客观情况要求"必须"，也可以翻译为"不得不"，have to否定形式意思是"不一定"或"没有必要"。