精加工不锈钢和铝合金应选用哪一种切削液
参考答案:精加工不锈钢时,应选用氧化煤油或75%煤油加25%油酸或植物油。 精加工铝合金时,可选用煤油或煤油与矿物油的混合油。
He tried to deal with the increasing burden of his work, but he finally ______ and had to take a complete rest.
[ ]
A. broke off
B. broke away
C. broke out
D broke down
获得性免疫缺陷综合征(AIDS)又称艾滋病,其致病病毒是()。
A.流感病毒
B.人类免疫缺陷病毒
C.轮状病毒
D.巨细胞病毒
E.疱疹病毒