放学了,当美羊羊提醒喜羊羊背上书包时,美羊羊应说:
A:Open your book.
B:Carry your bag.
C:Close your eyes.
数学在我们的生活中无处不在,就连小小的台球桌上都有数学问题.如图所示,∠1=∠2,若∠3=30°,为了使白球反弹后能将黑球直接撞入袋中,那么击打白球时,必须保证∠1等于____.
求下列各比的比值.
60:45
0.35: 16
20千克: 34 吨.
It was only after he had read the papers ________ Mr. Gross realized the task before him was extremely difficult to complete.