长期制动产生的关节损害包括（）

A.关节周围韧带的刚度降低，强度下降

B.滑膜增生、粘连

C.关节囊收缩

D.关节挛缩，关节活动范围减小

E.以上均正确

VHF Channel 6 is used exclusively for what kind of communications?（）

A.Radio checks and time checks

B.Inter-vessel safety and search and rescue

C.Working with helicopters

D.Radio direction finding