根据所给提示，完成句子，每空一词，含缩略词。

1. He has already finished his homework. (改否定句) 

    He ______ finished his homework _______.

2. The U.S.A had about 296 million people in 2005. (对划线部分提问)

    ______ the ______ of the U.S.A in 2005?

3. We must obey the school rules. (改为被动语态) 

    The school rules must ______  ______ by us.

4. I bought the pen six days ago. (同义句)

    ______  ______ six days since I bought the pen.

5. 我叔叔有时到上海出差.

    Sometimes my uncle go to Shanghai ______  ______.

BH1ZZZ希望加入两个电台正在通信中的谈话，正确的方法为（）

A.在双方对话的间隙，短暂发射一次“Breakin！”或“插入！”，如得到响应，再说明本台呼号“BH1ZZ等对方正式表示邀请后，方能加入

B.在一方正在发射期间，短暂插入一次“Breakin”，向正在收听的一方发出插入请求

C.短暂发射一次“Breakin！”或“插入！”，如对方无反应，应加大功率反复作此发射

D.只要双方都是自己熟悉的业余电台操作员，可直接插入谈话，不必拘泥礼节