题目内容：
The zoo keeper is worried because the number of visitors _____ smaller and smaller. A.become
B.became
C.is becoming
D.have become
参考答案：
选择题：The zoo keeper is worried because the number of vi
- 题目分类：河南理工大学-采矿工程-专升本英语1
- 题目类型：选择题
- 查看权限：VIP
A.become
B.became
C.is becoming
D.have become