— I suggest buying her a Teddy Bear for her birthday. —_____someone else brings the same present?
A:If
B:What
C:What if
D:How about
读我国地形示意图,回答下列各题:
如图所示,水平面上有一重为40N的物体,受到F1=13N和F2=6N的水平力的作用而保持静止.已知物体与水平面间的动摩擦因数μ=0.2.设最大静摩擦力等于滑动摩擦力,求: