— It's a pleasure to travel with you.
一 It's so kind of you to say so.
A:happy thing
B:difficult thing
C:terrible thing
函数y=12sinx+32cosxx∈0,π2的单调递增区间是____
城市水土流失对行洪排涝的影响有( )
将铜片放入0.1mol/LFeCl3溶液中,反应一定时间后取出铜片,溶液中c(Fe3+):c(Fe2+)=2:3,则Cu2+与Fe3+的物质的量之比为( )