公共场所中常见的病媒生物有（）、（）、（）、（）。
参考答案：苍蝇、蚊子、蟑螂、老鼠
关税的作用是( )。
A．保护国内工农业生产
B．调整产业结构
C．组织财政收A
D．调节进出口贸易活动
Mr. John wanted to go hunting, but he didn’t want to go fishing, ___.
A．so did his son
B．neither did his son
C．nor did his son
D．so it was with his son
