分类法是学习化学的有效方法之一．下列各组物质按照混合物、氧化物、单质的顺序排列的是（    ）

-2的相反数是（   ）

B) 根据语境，从方框中选择恰当的单词填空，并将正确答案填在短文后的横线上。

    To improve your English reading, you should, first of all, choose something you feel important or____ to read. Don't try to read everything. You should____ those written in easy English. Don't read those which is difficult for you at the very beginning.

    While reading, don't read too slowly or look up every new word you meet with. After reading a passage and having its main idea in mind, you may____ and read it again. This time you can read it slowly and look up some new words ____ necessary.

    Keep on reading in this way and you'll surely make____ little by little.