下列物质性质中，属于化学性质的是

    Hi, dear boys and girls! Do you know how to be a healthy kid? Here are some rules you should follow.

    First, eat different foods, especially(尤其) fruit and vegetables. You may have a favourite food, but you'd better eat something different, if you eat different foods, you will probably get more nutrients(营养物质) your body needs.

    Second, drink water and milk as often as possible. When you're really thirsty, cold water is the No.l choice(选择). Milk is a great drink that can give you more calcium(钙) your body needs to grow strong bones(骨头).

    Third, listen to your body. How do you feel when you are full? When you are eating, notice how your body feels and when your stomach(胃) feels comfortably full. Eating too much will not make you feel comfortable and make you fat.

    Fourth, limit(限制) screen time. Screen time is the time you watch TV, DVDs and videos, or using computers. It is good to take more exercise such as basketball, bike riding and swimming. You can't watch TV for more than two hours a day.

    Fifth, be active. One thing you'd like to do as a kid is to find out which activity you like best. Find ways to be active every day.

    Follow these rules and you can be a healthy kid.

阅读下面文言文，回答问题

鸣机夜课图记

【清】蒋士铨

      铨四龄，母日授四子书①数句。苦儿幼不能执笔，乃镂竹枝为丝断之，诘屈作波、磔②点画，合而成字，抱铨坐膝上教之。既识，即拆去。日训十字，明日，令铨持竹丝合所识字，无误，乃已。至六龄，始令执笔学书。

      记母教铨时，组绣纺③绩之具，毕陈左右；膝置书，令铨坐膝下读之。母手任操作，口授句读，咿唔之声，与轧轧相间。儿怠，则少加夏楚④，旋复持儿而泣曰：“儿及此不学，我何以见汝父！”至夜分，寒甚，母坐于床，拥被覆双足，解衣以胸温儿背，共铨朗诵之；读倦，睡母怀，俄而母摇铨曰：  “可以醒矣！”铨张目视母面，泪方纵横落，铨亦泣。少间，复令读；鸡鸣，卧焉。

     【注释】①四子书：《大学》、《中庸》《论语》、《孟子》。②波、磔（zhé）：汉字书写笔画。③组绣纺：即编织结线。④夏（jiǎ）楚：用于责打的大条等。

比较大小： ____2．