根据下面对话中的情境，在每个空白处填入一个适当的语句，使对话恢复完整。

A: Hi, Bob! How was your last weekend?

B: 1.                                         I really had a good time.

A: 2.                                        

B: I played basketball.

A: 3.                                    __

B: Twice a week. I like it very much. How did you spend your last weekend?

A: 4.                                   __

B: Sounds interesting. Do you often go to the mountains?

A: Yes. Once a week. 5.                                           

B: I'd love to. But I'm afraid I can't go with you this weekend. Maybe next week is OK.

战时，进入人防工程进行掩蔽的动作要求有哪些？