全喉切除后应做练习包括()
A.颈部放松
B.深吸气
C.缓慢均匀呼气的控制
D.腹直肌、腹斜肌等的协同收缩
E.胸廓扩张
参考答案:A, B, C, D, E
The old man is quite weak after the accident, so he _____ . [ ]
A. must take care of
B. must be take care of
C. must look after
D. must be looked after
质量为m的体操运动员,双臂竖直悬吊在单杠下,当他如图增大双手间距离时
A.每只手臂的拉力将减小
B.每只手臂的拉力可能等于mg
C.每只手臂的拉力一定小于mg
D.两只手臂的拉力总是大小相等、方向相反