动脉粥样硬化最常累及哪一支冠状动脉（）
A.左冠状动脉主干
B.左冠状动脉回旋支
C.左冠状动脉前降支
D.右冠状动脉心房支
E.右冠脉后降支
参考答案：C
看图完成小短文。
A. B. C.
Do you know the meanings of these signs? You can often see them in different places. Sign A
"SLOW" tells you not to drive too 1 . Sign B means that you mustn't turn 2 , but you can turn
3 _. Sign C can be seen in a museum. It means " _ 4_ Photos", so you mustn't _5 photos there.
1. _ 2. _ 3. _ 4. __ 5. _
为了自身目标而努力的经济单位，在努力的过程中使其他经济单位获得了意外的收益或损害的现象，指的是( )。
A．外部效应B．宏观效应C．微观效应D．内部效应
B. 
C. 