用一个平面去截正方形,其截面不可能是 [ ]
A.正方形
B.三角形
C.梯形
D.曲多边形
答案:D
— I'm afraid a car is too expensive for me.
— But more and more Chinese can _____ to buy it. [ ]
A. expect
B. afford
C. choose
D. offer
操作系统是一组( )。
A.文件管理程序
B.设备管理程序
C.资源管理程序
D.中断处理程序