“绿色化学”的核心是在化学反应过程或化工生产中，尽量减少使用或彻底消除有害物质．下列做法中，符合绿色化学的是（　　）

A．生产和使用剧毒农药

B．造纸厂用二氧化硫进行纸浆漂白

C．利用双氧水制氧气

D．化工厂产生的废气向高空排放

Read and guess.（读一读，猜一猜是什么季节）

It's very cold and it snows. We can make a snowman. Christmas is in this season.

1. __________

It's rainy and wet. Trees and flowers begin to grow.

2. __________

It's cool and foggy. Trees lose their leaves.  People can eat a lot of fruits in this season.

3. __________

It's hot and sunny. So people often go swimming in this season.

4. __________