填空题
A.F1保持不变,F3缓慢增大 B.F1缓慢增大,F3保持不变 C.F2缓慢增大,F3缓慢增大 D.F2缓慢增大,F3保持不变
A.108m/s2 B.1010m/s2 C.1012m/s2 D.1014m/s2