要测定空气中氧气的体积分数(如右图所示),放在密闭容器中燃烧的物质较合理的是
Thousands of houses _______ by the floods in Guangxi last month.
more, and you'll improve your spoken English.
--- I've just got a postcard from my pen friend. --- Let me have a look. Wow.nice card!
--- What is your favourite sport? --- Swimming, I think. It's of all.
---I use your ruler, Lingling? --- Sure. Here you are.