--- Shall we call on Frank tonight?
---We’d better not. He is said a lecture.
A. preparing
B. to be preparing
C. to have prepared
D. having prepared
网友回答
A. preparing
(答案→)B. to be preparing
C. to have prepared
D. having prepared
解析：考察非谓语动词.句意:我们今晚打电话给弗兰克吗?_我们最好别.据他说他正在准备一个演讲.不定式表示具体的将要进行的动作.结合语境可知不定式描述的是今晚正在进行的动作,故用进行时态的吧不定式.选B.