英语 完成句子（谈及他写的所有曲 speak）,i think this is probably his best-kn

英语 完成句子
（谈及他写的所有曲 speak）,i think this is probably his best-known one.
speaking of all the songs he has written 为什么要用完成时?那里看得出对现在的影响?
（切断电源 cut）quickly,he prevented an accident.
Cutting off the electricity 可不可以用：having cut off the electricity,为什么
it`s time that(他们开始认真对待你 take)and they are aware of that.
they began to take you seriouly,为什么用began?
还有像it`s time that和 it was time that 用法有没有什么规律?
i`d rather you (没有告诉她那消息 tell).how sad she is!
didn`t tell he that news这不是对过去事实的否定吗?为什么不用过去完成时?
HE（一进房间 get）when the telephone rang.
had hardly got into the room为什么是过去完成?如果用about怎么用?
even if是介词还是连词?