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