在“验证碰撞中的动量守恒”的实验中称得入射小球1的质量m1="15" g，被碰小球2的质量m2="10" g，由实验得出它们在碰撞前后的xt图线如图1-4中的1、1′、2′所示，则由图可知，入射小球在碰前的动量是___________g·cm/s，入射小球在碰后的动量是___________g·cm/s，被碰小球的动量是___________g·cm/s，由此可得出结论___________.
图1-4
1 500 750 750 碰撞前后动量守恒
xt图象反映速度的变化情况，从中要读出速度的大小，并分析出碰前还是碰后的情况.
An analyst does research about cash flow statement and gathers the following information about an IT company (in millions).
| Cash at the beginning of 2011 | $490 |
| Cash at the ending of 2011 | $505 |
| Cash flows from operating activities in 2011 | $32 |
| Cash flows from investing activities in 2011 | $30 |
A. issued $47 millions in bonds in 2011.
B. repurchased $47 millions of its stock in 2011.
C. increased long-term assets by $47 millions in 2011.