A:石蜡+氧气 →点燃 二氧化碳+水
B:氧化汞 →加热 汞+氧气
C:磷+氧气 →点燃 五氧化二磷
D:碳酸钙+盐酸→氯化钙+二氧化碳+水
Mum:Mary. ____
Mary:It's very pretty.
Assistant: ____
Mum:Yes. ____
Assistant:It's $ 99.
Mum:Oh, that's expensive.
Assistant:Do you like that blue skirt?
Mary:Yes. ____
Mum:OK. How much is it?
Assistant:It's $ 50.
Mum: ____
A. Can I help you?
B. OK. I'll take it.
C. How do you like this dress?
D. I like blue.
E. How much is it?
我国面积最大的省级行政区是( )