-I have a stomachache. What should I do? -You _______ drink cold water and _______ eat too much.
A. had better not; shouldn’t
B. should; had better
C. had better; had better
D. shouldn’t; should
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You look pale. _______ have a good rest?
A. Why you don’t
B. Why are you
C. What about
D. Why don’t you
刚体在四个力的作用下处于平衡，若其中三个力的作用线汇交于一点，则第四个力的作用线（）
A. 一定通过汇交点
B. 一定不通过汇交点
C. 不一定通过汇交点
1、已知一物块重100N，放在水平面上，静摩擦系数为0.3，动摩擦系数为0.25.当作用在物块上的水平推力为40N时，物块受到的摩擦力为（）
A. 25N
B. 30N
C. 40N
D. 50N
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