He __________ everywhere for materials and finally his efforts paid off. The medicine __________ to be very effective.
A：looked; was proved
B：explored; was proved
C：sought; has proved
D：hunted; was proving
如果a、b互为倒数，x、y互为相反数，则5（x+y）﹣ab=（ ）
2.6×105kV=____ V；3×107Ω=____ MΩ
月球自转一周的时间与月球绕地球运行一周的时间相等，都为T0．我国的“嫦娥1号”探月卫星于2007年11月7日成功进入绕月运行的“极月圆轨道”，这一圆形轨道通过月球两极上空，距月面的高度为h．若月球质量为M，月球半径为R，万有引力恒量为G．
