分类方法在化学学科的发展中起到了非常重要的作用。下列分类标准合理的是（  ）
①根据酸分子中含有的氢原子个数将酸分为一元酸、二元酸等      ②根据反应中是否有电子的转移将化学反应分为氧化还原反应和非氧化还原反应    ③根据分散系是否具有丁达 尔现象将分散系分为溶液、胶体和浊液     ④根据反应中的热效应将化学反应分为放热反应和吸热反应  （    ）

阅读下面的古诗词，完成后面问题。
过零丁洋        文天祥
辛苦遭逢起一经,干戈寥落四周星。
山河破碎风飘絮,身世浮沉雨打萍。
惶恐滩头说惶恐,零丁洋里叹零丁。
人生自古谁无死？留取丹心照汗青。

书面表达。

My hobby

阅读理解

    Which of your hands do you use most ? Very few of us use both of our hands well. Most of us are right-handed. Only about five people out of a hundred are left-handed. New-born babies can take things with either of their hands, but in about two years they like to use their right hands. Scientists don't know why this happens. They have studied it. They think our animal ancestors(祖先) are right-handed. This may not be true. Monkeys are our closest relations in the animal world. Scientists have found that monkeys like to use one of their hands more than the other—but it can be either hand. There are as many right-handed ones. Next time you visit the zoo, watch the monkeys carefully. You'll see that some of them will swing(摆动)from their right hands and others will use their left hands. But most human beings(人类) use their right hands better and this makes life difficult for the left-handed ones. We live in a right-handed world.

Don’t let ____ in. I’m too busy to see ____.