三级医院的高级、中级、初级员工比例是()。
A.2:4:8
B.1:2:8
C.1:3:8
D.1:3:6
E.1:3:9
参考答案:D
Leaves are found on all kinds of trees, but they differ greatly ______ size and shape. [ ]
A. on
B. from
C. by
D. in
若贫油含苯超标,请分析原因,并说明处理方法。