氨基钠(NaNH2)是合成维生素A的原料。工业上将钠于97 ~ 100 ℃熔融,向反应容器中缓慢通入无水的液氨(NH3),再加热至350 ~ 360 ℃生成氨基钠和氢气。下列说法中,不正确的是()
A:钠可能与水反应
B:钠的熔点比铁的熔点低
C:维生素A中一定含有钠元素
D:反应的化学方程式为:2Na + 2NH3△2NaNH2 + H2↑
翻译词组。
go to the birthday party____festival time____in the year____my friends' birthdays____
单词拼写
People will three days a week in the future.
《观刈麦》中表现农民反常矛盾心理的语句是:____,____。
American people like to say "Thank you " or say something kind when others help them.People of many countries do so,too.It is a very good habit. You should say"Thank you'when someone passes you the salt on the table,when someone walking ahead of you keeps the door open for you and when someone says you always do your work well or you have a nice thing or your city is very beautiful.“Thank you”is used not only between friends,but also between parents and children,brothers and sisters. “Excuse me”is another short sentence they use.When you hear someone says“Excuse me”behind you,you know that someone wants to walk past you without touching you.It’s not polite to break(打断)others when they are talking.If you want to speak to one of them。say‘Excuse me’first,and then begin talking.You should also do so when you begin to cough or make any noise before others.Let‘s learn to say‘Thank you’and‘Excuse me’.