增强心肌收缩力的药物是（）
A.五味子
B.山茱萸
C.乌梅
D.石榴皮
E.肉豆蔻
参考答案：B
—When did Mr. Mott finish ________?
—He _______ at 10:00. [ ]
A. to write; finish
B. writing; finished
C. to write; finishes
D. writing; finishes
某同学用力推块石头却没有推动。该同学的推力对石头是否做功?为什么?
