A:8
B:12
C:18
D:5
- Tom, you look tired this morning. What's wrong?
- I was busy and I didn't go to bed _________ 12 o'clock last night
在用托盘天平称物体质量前发现,横梁上的指针偏向分度盘的右侧,为使天平平衡,应采取的措施是( )。
随着航天技术的飞速发展,我国已成功实现两次载人航天飞行。在火箭推动飞船上升阶段,下列说法正确的是( )