当分级浓度高时,粗矿粒沉降速度()。
A.快
B.慢
C.不变
参考答案:B
Unfortunately, the computer system ______ suddenly while they were searching for some
information on the Internet.[ ]
A. broke up
B. broke down
C. broke away
D. broke out
结构钢分为碳素结构钢和合金结构钢,以及含碳量较高的()、弹簧钢。