Two hours are too short for us to finish our homework.为什么用is

Two hours are too short for us to finish our homework.为什么用is Two hours is enough for us to finish the experiment为什么要用介词fo To finish the work in two hours is too hard for us.改成同义句 it is p______ for us to finish our work It'll take us [three hours]to finish our homework（对着框框里的提问） it takes him two hours to finish doing his homework为啥用doing? It takes him two hours to finish his homework.对two hours提问 It is i for us to finish this hard job in suth a short time It is ( )不可能的 for us to finish the work in such a short time the work is too hard for us to finish in a week,we need ___p I have to take two hours to finish my homework.和Please to he two weeks (is not) enough for us to finish this task.we need