麻烦举一些考时态（现在完成时，过去进行时，过去完成时）的句子

i havn't finished my homework yet 现在完成时绝对不能出现明显的时间！
i was playing computer when my mum went home 9 o'clock yesterday.过去进行时必须要有过去某一点的时间！
i had already finished my homework when my mum went home .过去完成时要有对应的过去式时态。如我昨天做完作业之前吃了晚饭，你现在表述的时候，做完作业应该是过去时，但是吃晚饭在做完作业之前就做完了，用过去完成时。

（1）定义：现在完成时用来表示现在之前已发生过或完成的动作或状态,但其结果却和现在有联系,也就是说,动作或状态发生在过去但它的影响现在还存在.
I have had no money to spend now.(含义是:现在我没有钱花了.)
Jane has laid the table.(含义是:简已经摆了桌子.)
Michael has been ill.(含义是:现在仍然很虚弱)
He has returned from abroad. (含义是:现在已在此地)
（2）定义： 现在完成时可以用来表示发生在过去某一时刻的,持续到现在的情况,常与for,since连用.
Mary has been ill for three days.
I have lived here since 1998.
注意： 1.现在完成时不能单独与准确时间连用，(如表示过去的时间状语）
如yesterday(morning、afternoon),last(morning、afternoon)等，除非与for,since连用.
2.现在完成时往往同表示不确定的过去时间状语连用
,如already, yet, just, before, recently,still, lately等:
He has already obtained a scholarship.
I haven't seen muc