坠落时足与臀部着地,脊髓损伤最常见的脊髓水平为()
A.C1~2
B.T10~12
C.L1~2
D.C5~7
E.L4~5
参考答案:C
—What's today's talk about?
—It's about how to be polite when we requests. [ ]
A. have
B. ask
C. make
D. order
(1)试作出运动员运动的v-t图象;
(2)求减速下降时的加速度(大小和方向);