当钻头直径小于5mm时，应选用（）转速，但进给量不能太大，一般用手动进给，否则容易折断钻头。
A.低
B.较低
C.中
D.高
参考答案：D
The farmers in the fields when it to rain.[ ]
A. worked;was began
B. were working;began
C. were working;was beginning
D. worked;began
麻黄杏仁甘草石膏汤主治证的病机是（）
A.肺热壅盛
B.风寒犯肺
C.痰热蕴肺
D.燥热伤肺
E.痰湿犯肺
