不定式的完成式、进行式和完成进行式这三类在考研题中出现的频率很高，要特别注意不定式的这三种形式
1、如果不定式所表示的动作与主要谓语所表示的动作(状态)(或几乎)发生或发生在主要谓语之后，那么用不定式的一般形式
He received a arm ele from the Australians and from his family ho had flon there to meet him.
In 1967, he arrived back in England, here a quarter of a million people ere aiting to ele him.
After all, eighty as a special birthday, another decade lived or endured just as you chose to look at it.
No suddenly she began to sob, holding herself in as if eeping ere a disgrace.
2、如果不定式所表示的动作(状态)发生在主要谓语动词或特定的某时间之前,那么不定式就要用其完成式
She feels relaxed to have finished riting her thesis before the deadline.
33)The Vikings are believed America.
[A] to have discovered[B] in discovering[C] to discover[D] to have been discovered
34)The students ere to at the auditorium before 1:30 pm, but the lecture as cancelled at the last minute.
[A] assembled [B] have assembled [C] assembling [D] be assembled
35)He as to the ne ambassador, but he fell ill.
[A] having telephoned[B] have telephoned[C] has telephoned[D] telephoning
3、不定式进行式表示主要谓语动词所表示的动作(情况)发生时,不定式所表示的动作正在发生
When he came in, I happened to be doing my experiment in the lab.
Why do you stand here?You are supposed to be orking in the orkshop.
4、不定式完成进行式表示其动词所代表的动作，在主要谓语动词所代表的动作之前一直在进行
The students from the Department of Sociology are said to have been investigating the possibility of producing the ne product.
They are quite happy to have been cooperating harmoniously ith us till no.
