根据对话内容，在空白处写出恰当的句子，使句子连贯完整。 所写句子应与所给的标点一致。（共5小题，每小题1分，满分5分）

John: Uncle Smith, this is John speaking. I’m sorry to call up so late, but may I speak to Jim?

Smith: Jim is out.           小题1:      

John: OK, please. Jim and I applied an adventure(冒险)tour competition on the Internet a week ago. Today I was told that we were accepted.

Smith: Oh, that must be dangerous.      小题2:     

John: Because we want to do sports and something exciting.

Smith: You’d better not.      小题3:      

John: Uncle Smith, don’t worry. We can take good care of ourselves.

Smith:          小题4:      

John: Yes. We are ready for it.

Smith: Good luck.

John:         小题5:      

Smith: OK. I’ll tell him to call you back later.

系统设计中需要周密的频率规划，基站需要多部不同载波频率发射机同时工作，设备多且容易产生信道间的互调干扰。（）