工业上，为使95.6%的乙醇变为100%的绝对乙醇，常常加入一种物质加热回流一段时间后蒸馏，得到99.5%的无水乙醇，这种物质是（　　）

    This is a map of our school. There are1 buildings in our school: a library, an office building, a class building, a dinging hall and a sports hall. The library is2the left of the class building. There3many books in the library. We study in the class building, and after class, we often read books in the4. Our teachers work in the5 . This is a building6 twelve offices. Four teachers are in one office. Our school is old,7we have a big sports hall. We8 in it. What's your favourite9? Let's play it in the sports hall. I 10 my school very much. It's very good.