红细胞沉降率
参考答案：红细胞沉降率 是指红细胞在一定条件下自然下沉的速率，简称血沉。
高山气候特点之一，是在一定高度范围内降水量随高度增加而（）。
One night 18 percent of the female officers on a police force were on duty. If 180 officers were on duty that night and half of these were female officers, how many female officers were on the police force ？（）
A.90
B.180
C.270
D.500
E.1，000
