下列计量单位属于SI导出单位的是（）。A.长度m B.密度kg/m3 C.质量kg

The speech from the new government is a __________ that major changes are on the way．

A．notice

B．feature

C．signal

D．mark

满足约束条件|x|+2|y|≤2的目标函数z=y-x的最小值是（    ）。

When the waiter saw the man in rags coming into the  restaurant, he looked down upon him but had

to offer some          service to him.    [ ]

A. unwilling                

B. willing      

C. wonderful                

D. excellent

滚装船装卸货时横倾角应小于：（）

A.3°

B.4°

C.5°

D.6°

（）是课堂教学的延续、拓展和深化，其目的在于巩固、消化和运用所学知识。

A.作业

B.提问

C.测验

D.练习