【提出问题】该烧杯内溶液中的溶质是什么?

世界上三种东西最宝贵——知识、粮食和友谊。我们要想取得优异的成绩，除了20%决定于智力因素外，还应该（   ）
①培养浓厚的学习兴趣       ②养成良好的学习习惯
③树立正确的学习目的       ④把所有时间都用有学习上 

根据短文理解，从A、B、C、D四个选项中选择正确答案填空。

    When learning new vocabulary, don't just memorize list of words. 1, try to make five sentences using each new word. Then use the new word as you can the first day you learn it. This way you will remember new words 2 longer.

    Practicing sounds, you know, is difficult—the “th” sound for example. Choose words that 3“th” and repeat them over and over again until you are comfortable with them. Let's try! This, that, those, them, think, thought, through, thin, thick.

    Read, read, read— in English, of course! Reading is one of 4 ways to increase your vocabulary and 5 your grammar in a natural and fun way. Be sure to choose topics or books you are interested in.

    When someone 6 in English, listen for the main point. If you 7 a word you don't understand, ignore (忽略) 8 and go on listening. If you stop and think about the word, you will miss 9 the person is saying.

    Always remember—Practice 10 perfect.

如图，⊙O的半径为r，⊙O₁、⊙O₂的半径均为r₁，⊙O₁与⊙O内切，沿⊙O 内侧滚动m圈后回到原来的位置，⊙O₂与⊙O外切并沿⊙O外侧滚动n圈后回到原来的位置，则m、n的大小关系是(     )