将质量分数为a%、物质的量浓度为c1 mol·L－1的稀H2SO4蒸发掉一定量的水，使其质量分数为2a%。此时溶液的物质的量浓度为c2 mol·L－1。则c1和c2的关系是( )
| A．c1＝2c2 | B．c2<2c1 |
| C．c2>2c1 | D．c2＝2c1 |
相关试题
She brought with her three friends, none of ______ I had ever met before. 
| A．them | B．who | C．whom | D．these |
I tried phoning her office, but I couldn’t _______. 
| A．get along | B．get on | C．get to | D．get through |
His sister left home in 1998, and _______since. 
| A．had not been heard of | B．has not been heard of |
C．had not heard of | D．has not heard of |
What do you mean, there are only ten tickets? There _____ be twelve
| A．should | B．would |
C．will | D．shall |
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