汽车从武平到龙岩,去时用了3小时,返回用了2小时,往返平均速度是______.
(1×2)÷(3+2),
=2÷5,
=25;
答:往返平均速度是25;
故答案为:25.
One third of the deer by the wolves last night.
A.was eaten
B.is eaten
C.were eaten
D.are eaten
有关胸外心脏按压的手法叙述错误的是()。
A.掌根置于胸壁,另掌交叉重叠
B.手指翘起,肘关节伸直
C.双肩、双臂与胸骨垂直
D.利用上身重量垂直下压
E.放松时双手方可离开胸壁