化学是一门以实验为基础的科学,正确的实验操作是完成实验任务的保证,下列做法中,不合理的是( )
A:滴瓶上的滴管使用后无需清洁,可以直接放回原瓶
B:氧气点燃之前,务必要进行验纯操作,以防止出现重大事故
C:稀释浓硫酸时,先将浓硫酸倒入到烧杯中,然后逐渐加水
D:做还原氧化铁实验时,先通一会儿一氧化碳,然后进行加热
A
Linda,14
My mother does most of the housework like cooking and folding the clothes.My father can only do the washing,sweep the floor and take out the rubbish.He really needs to learn how to do the housework.
Celina,13
My mother and my father do 50% of the housework each.My mother does the washing and cleans the living room.My father makes the bed and drives me to school.
Paul,16
My father doesn't do a lot but he tries to help.He hangs__up the clothes after my mother washes them and my mother is happy that he always gives her a hand.
Bill,15
My mother is a doctor.She is busy with her work every day,so she has little time to do the housework.In fact,she isn't good at doing it.So my father has to do most of it.Sometimes my grandmother comes to help.