Hello! My name’s John. I’m in Beijing now. It’s hot in Beijing. It’s sunny too.

I can wear my shorts and shirt. My shorts are green. I have a new jacket. My old jacket is too small. I want to buy a hat.The hat is very pretty, but it is $60. that’s very expensive.

The hat is cheap.

向澄清的石灰水中吹气，石灰水变浑浊了，这个实验说明呼出的气体中含量一定增加的是（　　）