磁盘操作系统的简称是()
A.OS
B.DOS
C.OP
D.DS
参考答案:B
Please be quick, or we will have no time ____ have lunch. [ ]
A. to
B. in
C. on
D. /
罐笼有单层罐笼、双层罐笼和三层罐笼三种。