苏联的天体物理学家也管黑洞叫做()
A、暗黑星
B、冻结星
C、石化星
D、乌有星
参考答案:B
Before 2003, there was no direct airline _____ Taiwan and the mainland. [ ]
A. along
B. in
C. between
D. at
YJ27滤嘴接装机滤棒切刀磨刀砂轮调节手轮()方向转动,可减小磨刀压力。