—________is it ________ had made our headteacher that angry?— Six of us being late this morning.

题干

—________is it ________ had made our headteacher that angry?
— Six of us being late this morning.

A：What; what

B：That; that

C：What; that

D：What; which

上一题下一题 0.0难度选择题更新时间:2010-06-02 08:40:34

C

铜镁合金具有优良的导电性，常用作飞机天线等导电材料．欲测定合金的组成（其他元素忽略不计），进行如下实验：取铜合金20g放入烧杯，将280g稀硫酸分4次加入烧杯中，充分反应后，测得剩余固体的质量记录如下。请计算：

（1）合金中铜、镁的质量比；
（2）所加稀硫酸的溶质的质量分数。（写出计算过程）