—Could you tell me _______ it takes to go from here to Harbin by car?—About fifty minutes.
A:how long
B:how much
C:how many
D:how often
我国夏季气温最低的地方是( )
如图所示,A、B两小球从相同高度同时水平抛出,经过时间t在空中相遇,若两球的抛出速度都变为原来的2倍,则两球从抛出到相遇经过的时间为( )