题目

Sean:  What a fine day! Oh, I can spend all my free time   11    (read) on this balcony on a fine day like this. I like it. Jean:  The balcony is very beautiful, but I don’t like the fact that it   12    (face) north. Sean:  Why? What’s wrong with its facing north? Jean:  You don’t know that   13    the balcony faces north, it will get cool in the summer, but too cold in the winter. Sean:  You don’t have to worry about that. We have the  14   (center) heating system in winter, don’t we? Jean:  Yes, we do. The best houses face south, anyway. In that c为测定某ＮaCl、Ｎa2CO3固体混合物的组成，小明同学取１６g该混合物放入烧杯中，分五次加入稀盐酸（每次加入稀盐酸的质量为２５g），待反应完全后，得到下面的质量关系：请分析以上数据后计算：⑴原固体混合物中Ｎa2CO3的质量。⑵当加入稀盐酸至固体混合物恰好完全反应时，所得溶液的溶质质量分数。（计算结果精确到０.１）