hear的过去式怎么变

　　He could hear someone moving around in the room above.

　　他能听到楼上屋里有人走动。

　　It was three weeks later that he heard the news.

　　三个星期之后他才听到这个消息。

　　Many's the time I heard her use those words.

　　我不止一次听她说过那样的话。