问题补充:
--Alice, why didn you come yesterday?
--I , but I had an unexpected visitor.
A. had
B. would
C. was going to
D. did
答案:
A. had
B. would
C. was going to
D. did
解析:当不定式在某些结构后作复合谓语时,不定式符号 to后的内容可以省略。常见的结构有:be able to,be going to,have to,ought to,used to等。