题型:选择题 如图所示,水龙头开口处A的直径d1=2cm,A离地面B的高度h=75cm,当水龙头打开时,从A处流出的水流速度v1=1m/s,在空中形成一完整的水流束.则该水流束在地面B处的截面直径d2约为(g取10m/s2)( )A.2 cmB.1 cmC.1.5 cmD.0.5 cm 查看答案
题型:选择题 — Hasn't the thief admitted his crime by now? — No, ______ questioned many times. [ ]A. if B. though C. unless D. once 查看答案