体育课上同学们进行爬杆比赛,某同学沿竖立的硬竿匀速向上爬,该同学受到的力中与他所受的重力相平衡的力是
A:摩擦力
B:拉力
C:臂力
D:压力
I feel strongly that each of us has a part ____ ____ in making China more powerful.
machine.
16+8×(70-50)=____
(16+8)×70-50=____