小明买了20本练习本，店主给他八折优惠，结果便宜1.6元，每本练习本的标价是____元 。

下列生物的生殖现象属于出芽生殖的是（　　）

①a阶段为有丝分裂、b阶段为减数分裂

②M点所示过程与细胞膜的流动性有关

③GH段和OP段，细胞中含有的染色体数是相等的

④MN段发生了核DNA含量的加倍

Should teenagers be asked to move out when they start working? People in different countries have different ____.

In many Western countries, teenagers are allowed to move out at the age of____. Their parents believe that they should be____ to care for themselves from an early age. In this way, when they start working, they can  ____

their own lives. In most Asian societies,____,it is not common for teenagers to move out. Chinese parents believe that ____  is better for children to live with parents who can take care of them. But the young should then look after their parents when they get____. That is why many Chinese adults continue to live with their parents, even ____ they get married.