股四头肌可()
A.屈膝关节
B.伸膝关节
C.膝关节旋内
D.膝关节旋外
E.限制伸膝关节
参考答案:B
A.mgtgθ
B.mgsinθ
C.μmg
D.μmg
Good anchorage may be obtained anywhere in this water area,the bottom being generally mud and sand,vessel may have().
A.good getting ground
B.good holding ground
C.good grabbing ground
D.good handling ground