If you don't study hard, you won't ______ other students. [ ]

A. come up with

B. catch up with

C. agree with

D. play with

临产后起主要作用的产力是（）

A.子宫收缩力

B.腹肌收缩力

C.膈肌收缩力

D.肛提肌收缩力

E.球海绵体肌收缩力