I hate travelling by air_______ you usually have to wait for hours before the plane takes off.

A．because

B．though

C．until

D．Unless

下列关于双侧髁状突骨折的临床表现，正确的描述是（）

A.下颌不能做前伸运动

B.下颌侧颌运动受限

C.后牙早接触

D.前牙开

E.双侧颞颌关节区压痛