1是所有自然数的因数.______.
根据分析,1是所有自然数的因数.说法正确.
故答案为:正确.
《建设工程监理规范》规定,( )属施工阶段的管理资料。
A.施工组织设计
B.勘察设计文件
C.工程定位测量资料
D.建筑物沉降观测记录
The students can't go out ________ school nights, but they can ________ Saturdays and Sundays. [ ]
A. in; in
B. on; on.
C. in; on
D. on; in