水闸启闭控制系统检查安全鉴定的周期，按现有行业规定，首次安全鉴定应在竣工验收后5年内进行，以后应每隔（）年进行一次全面安全鉴定。

A、6

B、8

C、10

D、12

补全对话。

A: Good afternoon!

B: Good afternoon!

A: Can you paint?

B: Sorry, 1_______.

A: So many clubs here. 2_______?

B: I’m not sure.

A: Can you 3_______ chess?

B: Yes, but not very well.　4_______?

A: I can play it well, but I like singing very much. So I want to join  5_______.

B: Me, too. I think we can go to the music club together.