钻井液除砂器一般能清除约95拆粒径大于74卜门和50刃粒径在()的岩属。
A.74一94μm
B.40一74μm
C.15一40μm
D.12一13μm
参考答案:B
I don't think difficult for a Chinese student to master a foreign language within five years
A.that
B.it
C.too
D.very
七情中,表示减毒配伍关系的是()
A.相须、相使
B.相杀、相畏
C.相恶、相反
D.相杀、相反
E.相畏、相使