题目内容：
Many students at the school _______ on a project which relates to the unemployment problem.选择一项：
A.
worked
B.
have worked
C.
have been working
参考答案：
选择题：Many students at the school _______ on a project w
- 题目分类：国家开放大学人文英语2
- 题目类型：选择题
- 查看权限：VIP
选择一项：
A.
worked
B.
have worked
C.
have been working