+水 ◇+○
A:麦芽糖
B:乳糖
C:蔗糖
D:B或C
如图所示,在一水平地面上,木箱重500N,用F=150N的力拉动木箱做匀速直线运动(不计滑轮重量及绳与滑轮间的摩擦),木箱受到的摩擦力为 ____ N,方向向____ .
①Jills wish autumn the bright moon in the garden catch the fish
②what do you have i have some pairs of blue shoes