jam的過去式和過去分詞

　　例句：

　　The fruit can be made into jam.

　　這種水果可以制成果醬。

　　People are fed up with all these traffic jams.

　　人們厭煩這么多的交通堵塞。

　　The valve has jammed shut.

　　閥門給卡住了打不開。