不定式的完成式、進(jìn)行式和完成進(jìn)行式：這三類(lèi)在考研題中出現(xiàn)的頻率很高，要特別注意不定式的這三種形式

　　1、如果不定式所表示的動(dòng)作與主要謂語(yǔ)所表示的動(dòng)作(狀態(tài))同時(shí)(或幾乎同時(shí))發(fā)生或發(fā)生在主要謂語(yǔ)之后，那么用不定式的一般形式

　　He received a warm welcome from the Australians and from his family who had flown there to meet him.

　　In 1967, he arrived back in England, where a quarter of a million people were waiting to welcome him.

　　After all, eighty was a special birthday, another decade lived or endured just as you chose to look at it.

　　Now suddenly she began to sob, holding herself in as if weeping were a disgrace.

　　2、如果不定式所表示的動(dòng)作(狀態(tài))發(fā)生在主要謂語(yǔ)動(dòng)詞或特定的某時(shí)間之前,那么不定式就要用其完成式

　　She feels relaxed to have finished writing 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 were to at the auditorium before 1:30 pm, but the lecture was cancelled at the last minute.

　　[A] assembled [B] have assembled [C] assembling [D] be assembled

　　35)He was to the new ambassador, but he fell ill.

　　[A] having telephoned[B] have telephoned[C] has telephoned[D] telephoning

　　3、不定式進(jìn)行式表示主要謂語(yǔ)動(dòng)詞所表示的動(dòng)作(情況)發(fā)生時(shí),不定式所表示的動(dòng)作正在發(fā)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 working in the workshop.

　　4、不定式完成進(jìn)行式表示其動(dòng)詞所代表的動(dòng)作，在主要謂語(yǔ)動(dòng)詞所代表的動(dòng)作之前一直在進(jìn)行

　　The students from the Department of Sociology are said to have been investigating the possibility of producing the new product.

　　They are quite happy to have been cooperating harmoniously with us till now.