下列操作既能加快硝酸钾的溶解速度，又能增加硝酸钾溶解质量的是（　　）

   Many parents make their children do chores around the house. For some families, teaching children what to do and how to do chores is easy. But in other families, getting children to do some housework can be a very big problem.
   It is a good idea for parents to teach their children at an early age. All family members must work together to make the house clean, and each person must do his or her share(份) of the work. We can do this by starting plan of chores and responsibilities(责任) when children are young.
   Chores are good for children—even very young ones. Doing chores can teach children many important skills(技能) like working together. Jobs also teach children what is fair(公平). The skills and value(价值) from doing chores will be good to children all their lives. 

依次填入下面文字中横线处的关联词、副词，最恰当的一项是（     ）

    她没有漂亮服装，没有珠宝，什么也没有。     她      只喜爱这些······她有一个有钱的女朋友，是教会女校的同学，     她再也不想去看望她了，      看望回来就会

感到十分痛苦。       伤心、悔恨失望、困苦，她常常整天整天地哭泣······

正方形的四条边____。