胸部外伤后最常见的两种症状为（）？
A.胸痛和休克
B.胸痛和呼吸困难
C.呼吸困难和咯血
D.休克和咯血
参考答案：B
辩论原则
The secretary is very careful and never ________ any little points.[ ]
A. notices
B. deletes
C. overlooks
D. undertakes
