单项选择题 下列属于中央处理器（CPU）的结构是（）。

单项选择题 一个EXCEL文件下默认的工作表有（）个。

单项选择题 下列问题是是基于如下两个关系，其中供应商关系S的主键是供应商号，零件关系P的主键是零件号，而且P关系中的颜色值只能为(红，白，蓝)。下面列出的操作，不能成功执行的是______。

单项选择题 The major problem with E-mail is that it is (1) easy to use that people can become (2) with messages. (3) they can possibly answer in a day. In addition, mail boxes require some management to (4) messages or archive those that might be required later. Senders don't always know about your E-mail backlog and often send (5) messages.

单项选择题 下图为某工程进度网络图。结点1为起点，结点11为终点，那么关键路径为(1)，此工程最快(2)天完成。(1)