He __________ goes to Tai'an, so he wants to go there.
A:always
B:never
C:not
D:usually
——This is story I've told you about several times.——It's great. I've never heard more moving one.
如图,手拉着木块在粗糙程度不变的水平面上做加速运动,则木块受到的摩擦力大小( )