— ?
— They are my books.
A:What are these
B:What's this
C:How are you
D:Where are you
一字组多词。
力:____、____、____
如图,分别用力F1、F2、F3将质量为m的物体沿同一光滑斜面以相同的速度从斜面底端拉到斜面的顶端,在此过程中,F1、F2、F3做功的功率大小关系是( )