质量为m的物体放在质量为M的斜面上,斜面体放在水平粗糙的地面上,m、M均处于静止状态,如图所示,当在物体m上施加一个水平力,且这一力由F突然增加到F′时,m和M都仍保持静止状态,关于水平力作用下的这两个平衡状态,下列说法正确的是( )
A:斜面体对m的支持力不变
B:物体m受到的摩擦力可能减小
C:地面受到的压力不变
D:地面对斜面体的摩擦力可能减小
某数除以7有余数.余数最大是____
Rules of visiting the Science Museum
Rules
1).First, don't ____ in the museum, or the workers in the museum will ask you to leave.
2). Second, you mustn't take ____ in the museum. But you can take a pen and a notebook to write down some ____ information.
3). Third, follow the guide and don't leave ____ the teachers.
4). Finally, keep the museum clean and tidy while visiting.
Way of contact
Call ____if you have any more questions.
治理黄河的根本措施是( )