题目内容：

用括号内所给动词的适当形式填空。

1.I ________ (read) a novel last night when I heard knocks at the door.

2.The young man ________ (live) alone since he graduated from college.

3.Be careful ___________ (not fall) off the ladder.

4.The actor and director ________(be) coming to give us a speech next weekend.

5.I overslept this morning. By the time I got to the train station, the train ________ (leave).