I feel happy when I Finished my homework //为什么不用过去完成时?

I feel happy when I Finished my homework //为什么不用过去完成时? I have finished my homework.可否这么说 I finished my homework.为什么 I have finished my homework.When _____you_____it?怎么添? I have finished my homework.When _____you_____it?为什么填didi,fi I have finished my homework I have finished my homework.将其改为过去完成时,在改为一般疑问句, I feel happy when I help others. I finished my homework.when I went to bed.(合并为一句) I have finished my homework.反义疑问句 i just finished ___ my homework. I've finished my homework already I just finished my homework.同义句