根据首字母或汉语提示写出单词。

1. Why don’t you tell US what r______ happened?

2. —Would you like some bread or cookies?

    —N______, thanks. I don't have any food before going to bed.

3. I left my g textbook at home yesterday.

4. People should be taken a p______ examination every year.

5. What ______(科目) are you studying at school?

下面不是电子商务运行与维护主要内容的是( )。

A．应用软件维护

B．数据维护

C．系统运行维护

D．操作系统的维护