雷电天气里，人们躲在什么样子的屋子里才最安全(    )。

根据短文内容及首字母提示完成短文，使短文完整、通顺

In America, we go to s____from Monday to Friday. On school days, I     g____up at seven and have my breakfast at half p____seven. Our lessons  s____at eight. And we d____have many lessons in a day. At half past eleven, we have a b____and then we have our l____at school. In the afternoon, we finish school at about three. Then we can g____home. But many boys in my school l____to play football in the playground after school.

What a____your school day?

物质的用途和性质密切相关。下列用途主要是利用其化学性质的是（）