氮化硼（ BN）是一种重要的功能陶瓷材料．以天然硼砂（主要成分Na₂B₄O₇）为起始物，经过一系列反应可以得到BN和火箭高能燃料及有机合成催化剂BF₃的过程如下：

Sarah: We're going on a trip. What do you want to wear?

Mike: I want to wear my pants and sweater. What about you? 

Sarah: I want to wear my skirt and dress. And I need a hat.

Mike: Oh! It looks nice. I can take my shirt and shoes.

Sarah: I will take my jacket, too.           

例如：Whose skirt is it?  It's Sarah's skirt.

根据划线单词提问。

把菠菜放入冷水中几分钟，水不会变成绿色，如果把菠菜放入沸水中煮几分钟，水会变成绿色．这是由于高温破坏了（　　）

注意发：每句只有一处错误多改不计分。

    It was extreme cold last Monday morning. While I was walking in my way to school, I noticed two street cleaner sweeping the street. Seeing them are working so hard on such a cold morning, I was moved and made up my mind do something for them. After arriving at school, I discussed with some classmates that we could do. The next day, we got up early and preparing porridge at home. When we handed the cleaners the hot porridge and expressed us appreciation for their hard work, they looked a little surprising at first. And then they took the porridge and thanked us happily. Since it was very cold, we all felt warm at that moment.