类推的思维方法可解决不少化学问题，但类推的结论最终要经过实践的检验才能确定其正确与否．下列几种类推结论中，你认为正确的是（ ）
A：沸点HBr＞HCl，则同族元素氢化物沸点HCl＞HF
B：Fe3O4可表示为FeO•Fe2O3，则Pb3O4可表示为PbO•Pb2O3
C：CO2与Na2O2反应只生成Na2CO3和O2，故SO2与Na2O2反应也只生成Na2SO3和O2
D：SiO2能形成原子晶体，一定条件下CO2也能形成原子晶体
A：Hey,Rita!What is your new school like?
B：It's big and nice．
A：____
B：Yes,it does．
B：We must get to school before 8：00 a．m.We can't eat in the classroom．
B：Yes．we do.
B：No,we can't．
B：Very good．I think they're good for us．
A：Do you have fun at your new school?
B：Yeah!
A．Can you wear your hats in class?
B．Does it have many rules?
C．What canyoudo?
D．What are the rules?
E．Can I help you?
F．Do you have to wear your uniforms at school?
G．What do you think of these rules?
在△ABC中，若a=3,cosA=-12，则△ABC的外接圆半径是( )
将一根枝条插入滴有红墨水的瓶中，放在太阳下一段时间后，将枝条纵切开来，用放大镜可看出哪一部分被染红了（ ）
