急性呼吸窘迫综合征（ARDS）常发生于原发病后（）。
A.48h内
B.48h后
C.3d以后
D.5d以后
E.7d以后
参考答案：A
---Why do you look so upset?
---There are so many troublesome problems _____.
A．remaining to be settled
B．remained settled
C．remaining to settle
D．remained to be settled
避让行动有效性的核查适用于下列哪些船舶（）？
A.让路船
B.直航船
C.让路船和直航船
D.任何构成碰撞危险的船舶
