I will wait here ____ the concert is over. [ ]
A. by
B. when
C. until
D. as
答案:C
直接暴力可引起
A.粉砟性骨折
B.病理性骨折
C.疲劳性骨折
D.压缩性骨折
E.撕脱性骨折
A.mgtgθ
B.mgsinθ
C.μmg
D.μmg