( )六边形硬百叶窗拼装方法：先将三根窗框拼装成一体，然后插入百叶板，最后将另三根拼成一体的窗框拼装上去。
参考答案：对
All the books donated by the students from urban schools are said _____ to the students in rural areas
the other day. [ ]
A. to be sent
B. being sent
C. having been sent
D. to have been sent
我国高校教师的职务分为（）级。
A．三
B．四
C．五
D．六
