It’s so nice of you to help me with my homework.
你真是太好了,帮助我完成作业。
It’s very difficult for me to do the math homework.
数学作业对于我来讲太难了
It takes my mother all day to do the housework.
做家务花了我妈妈一整天的时间。
I have so many homework to do.
我有许多作业要做。
enough+名词+to do
eg: It’s difficult enough to do my math homework. 数学作业太难了。
“It’s time to do sth.”
eg: It’s time to go home. 是时候回家了。
I go to bed early in order to get up early in the next day.
我那么早睡觉就是为了第二天能早起。
My little brother is too young to go to school. 我的弟弟太小而不能上学。
动词不定式作主语时,可以直接放在谓语动词前面的主语位置,也可以用先行词it作形式主语,而将真正的主语(不定式)置于后面。常见的句式有:(1)It is +形容词(of sb)to do sth.(2)It is +名词(for sb)to do sth.(3)It takes sb some time to do sth.(4)It is +形容词(for sb)to do sth.句式(1)中常用nice, kind, clever, good, right, wrong, foolish, careless等形容词,与介词of搭配,这些形容词常表述不定式逻辑主语的属性或性质;句式(4)中常用hard, difficult, easy, important等形容词,与介词for搭配,表示不定式表示的动作、行为的性质。