CAT表示()。
A.晴空乱流
B.航空器尾流
C.高空急流
D.卷云
参考答案:A
We were greatly _____ in our investigation by the cooperation of the police.[ ]
A. exposed
B. submitted
C. aided
D. switched
流行病学研究对象的三个层次包括
A.虚弱
B.疾病
C.伤残
D.伤害
E.健康