船在江中顺水航行与逆水航行的速度之比为7:2,那么它在两港间往

船在江中顺水航行与逆水航行的速度之比为7:2,那么它在两港间往返一次的平均速度与顺
水速度之比为(      )。
 
A.B.C.D.

答案

解析:
略p;【解析】略

相关题目

下列有关物质分类或归类正确的是(    ) ①混合物:石炭
下列有关物质分类或归类正确的是(    ) ①混合物:石炭酸、福尔马林、水玻璃、水银②化合物:CaCl2、烧碱、聚苯乙烯、HDO ③电解质:明矾、胆矾
下列叙述完全符合质量守恒定律的是 ( ) A.水结成冰前后
下列叙述完全符合质量守恒定律的是 ( ) A.水结成冰前后,质量保持不变B.50 mL水和50 mL乙醇混合后总体积小于100 mL C.在100 g过氧化氢溶液中,含有30 g
  When students and parents are asked to rate subjects according to their impor
  When students and parents are asked to rate subjects according to their importance, the arts are unavoidably at the bottom of the list.Music is nice, people seem to say, but not important.Too o
二氧化碳和氢气在一定条件下反应能生成一种可燃性气体X,
二氧化碳和氢气在一定条件下反应能生成一种可燃性气体X,其反应的化学方程式为:,则X的化学式为A.COB.H2 C.CH4D.C2H4
He ______ at the meeting, but his heart attack prevented him. A.will speak   
He ______ at the meeting, but his heart attack prevented him. A.will speak                             B.is going to speak C.had to speak                  
If you are able to talk to a friend over the telephone, you feel that you are cl
If you are able to talk to a friend over the telephone, you feel that you are close _____ the actual distance is not shortened. A.even if           B.so long as            C
下图所示实验操作正确的是( ) A. 检查装置气密性  B.
下图所示实验操作正确的是( ) A. 检查装置气密性  B. 往试管中加入锌粒 C. 加热液体    D. 固体药品的取用
若带正电的小球只受电场力的作用,则它在任意一段时间内(
若带正电的小球只受电场力的作用,则它在任意一段时间内(    )   A.一定沿着电场线由高电势向低电势运动   B.一定沿着电场线由低电势向高电势

最新题目