计算下列各题(能简算的写出简算过程)。

① $\frac{1}{8}+\frac{5}{7}+6.875+\frac{2}{7}$               

② $\frac{7}{9}÷\frac{11}{5}+\frac{2}{9}\times \frac{5}{11}$

③ $\frac{1}{3}÷(\frac{2}{3}-\frac{2}{5})\times \frac{3}{5}$               

④ $\frac{1}{2}-(\frac{3}{4}-\frac{3}{5})$ $÷\frac{7}{10}$

中央决定放开“单独二胎”，即一方独生子女夫妇可以生育两个孩子。国家卫生计生委昨日发文称，这是我国进入21世纪以来生育政策的重大调整完善，是国家人口发展的重要战略决策。同时也（）
①说明我国已不需要计划生育的基本国策了  
②可缓解人口老龄化的情况。
③将导致人口暴涨                        
④顺应了群众期盼，有利于社会和谐稳定。 

      There are  1 days  2 a week. They are  3 , Tuesday, Wednesday, Thursday, Friday, Saturday and4  .Sunday is the first day 5 a week. Monday is the second day of a week. The last day of a week is Saturday.  6  China, people work 7days a week. They go to work from Monday 8  Friday. They don't go to work 9 Saturdays and Sundays . They stay 10  home.