基牙B4常用哪类卡环（）
A.单臂卡环
B.间隙卡环
C.三臂卡环
D.双臂卡环
E.下返卡环
参考答案：B
汽车列车的车身越长，转弯半径越小。
Typhoon Morakot swept across Taiwan on August 8. 2009, _________hundreds of people dead or missing.
A．leaving
B．left
C．to have left
D．having been left
