开口型指的是（）
A.张口的大小
B.上下唇之间距离
C.上下切牙切缘间的距离
D.下颌下降运动时颏点的运动轨迹
E.下颌骨的活动度
参考答案：D
It took him three hours to ________ all the homework. [ ]
A. finishes doing
B. finish doing
C. finished did
D. finished do
长条形灯具是指它的发光面长宽比大于( )的灯具。
A．2:1 B．3:1 C．3:2 D．4:3
