A:was able to
B:had to
C:is able to
D:has to
在下列数字后填上合适的单位:一本苏科版九年级(下)物理课本的质量大约为235 ____.刘翔在雅典奥运会110m栏决赛中夺冠的平均速度为8.52 ____
—Can you help me with my maths?
—_______, I know _______ about it.