根据对话内容，在空白处填写适当的话语（话语可能是一个句子，也可能是一个短语或一个词），使对话完整。

Jan:   I don't want to learn Chinese any longer!I can't learn it well!

Beth:  Don't 1._________. Keep trying.  Learning a language isn't easy.  It takes a lot of time  and effort.

Jan:   I can't do it．

Beth:  Remember the old saying, "Time on task!" Work hard at it, and 2._________.

Jan:   I have difficulty with the four tones（音调）.  No matter how hard I try, my pronunciation is poor.  My Chinese sounds awful.

Beth:   "Try ,try and never say die." Listen to simple songs and watch Chinese-languagemovies. Read easy anf interesting Chinese stories that have tapes or CDs.You'll learn to.3._____Chinese.  That's a promise (希望).                           

Jan:   4. _________

Beth:   "Try ,try and never say die." Listen to simple songs and watch Chinese-languagemovies.Beth:  Of course.  We're friends, and that's what friends are for.  Don't worry.Beth: You are welcome.

工业上以大理石和磁铁矿（Fe₃O₄）为主要原料可以制取B和G，其转化关系如图所示，已知D、G的主要成分为单质．试回答下列问题：

（1）写出工业制取的两种物质的化学式：B______、G______．

（2）写出下列反应的化学方程式：

反应①：______；

反应③：______；

检验气体C：______．