呵,这个容易,现在时变完成时,只需在该动词前面加上助动词have,had,has,然后再将该动词do改为过去分词done就行了,举个例子：we win the game right now -----we had won the game yesterday.怎么变比如说know哦，容易啊，know的话，可以这样：现在时I know the news. 变完成时就是：I had known the news. 其中，known 就是know 的过去分词形式。不懂还可以再问哦，