Unit5 Animals-grammar 素材动词不定式的时态、语态形式如下（注意否定时 not 的位置）： 一般式 （not） to do （not）to be done完成式 （not）to have done （not）to have been done进行式 （not） to be doing完成进行式 （not） to have been doing1)时态 （1） 一般现在时：不定式一般现在时表示的动词，有时与谓语动词表示的动作同时发生，有时发生在谓语动词的动作之后。 He seems to know this. I hope to see you again. We hope to build up a modern laboratory before long. （2） 完成时：不定式表示的动作发生在谓语动词表示的动作之前。 I'm sorry to have given you so much trouble. I'm sorry to have kept you waiting so long． （注意区别：I am sorry to keep you waiting. Don’t leave ,please.）He seems to have caught a cold. They are known to have come to a decision on the matter. It was a great satisfaction to have visited our native village. ★注意特例：You should(ought to） have switched off the light when you left the classroom. 你离开教室的时候应该把灯关掉。（实际上没有关灯,是虚拟语气） Ex(Choice):① Some people were reported ____ flying saucers that same evening. a. to b. to have seen c. to have been seen d. having seen ② The elephants ought ____ hours ago by the keepers. a. to be fed b. to feed c. to being fed d. to have been fed （3） 进行时： 不定式表示的动作正在进行，与谓语动词表示的动作同时发生。 He seems to be eating something. The water seems to be boiling. She was found to be teaching the pupils to make model planes. The teacher happened to be correcting our papers when I came in. （4） 完成进行时：不定式表示的动作在谓语动词表示的动作之前开始发生，并延续到那个时候，可能仍在进行。 She is known to have been working on the problem 用心 爱心 专心for many yearsShe seems to have been writing a scientific treatise. 2）语态 (1)主动式：表示主动的意义...
