把质量相等的两种液体(密度分别为ρ1、ρ2)混合,设混合后的总体积不变,则混合液体的密度为( )
A:ρ1+ρ22
B:ρ1ρ2
C:ρ1ρ2ρ1+ρ2
D:2ρ1ρ2ρ1+ρ2
——I hope to see Niagara Falls one day. What about going there?——Niagara Falls would be beautiful, but there is not much to do there.
把温度计的玻璃泡用棉花包上,蘸上酒精,酒精蒸发时温度计的示数 ____(填上升、下降或不变),这是因为蒸发 ____的缘故.
分解因式:(p+1)(p﹣4)+3p=____.
If you _________ an order, you follow the order and do what it asks you to do.