A poor farmer had a friend who was famous for the wonderful apples he grew. One day， his friend gave him a young apple tree and told him to take it home and 1 it.

    Seeing the gift， the farmer was very happy， and he thought he would also have a lot of wonderful apples， but when he got home， he felt 2 . He did not know where to plant it. He thought over and over and considered every place he could think of. 3 ， he decided to plant the tree in his woods. There were many high trees with thick leaves in the woods. With those trees around ，no one else could see the young apple tree. He even felt proud of himself for finding so secret a place for the apple tree. Every day he went to take care of the tree， watering it. To his surprise and 4， the apple tree didn't grow as well as he expected.  It died without sunlight and good soil.

    Later the friend asked the farmer why he had planted the tree in such a 5place. "What's the difference?" the farmer said angrily. "If I had planted the tree near the6， passers-by(行人) would have stolen the fruit. If I had planted the tree in one of my fields， my neighbors would have come at night and 7 some of the apples! If I had planted it near my house， my own children would have taken the fruits. No matter where I plant the tree， I can't have8 to enjoy the apples： So there is no difference where I planted it."

    "Yes，" said the friend. "But sooner or later someone could have enjoyed the fruit. Now you not only have robbed(抢夺) everyone of the fruit， but also have 9 a good apple tree! You don't know the true meaning of 'share'!"

    We should learn to 10in our life. The more you want to own something all by yourself， the less you get at last.

【实验一】他将理发店收集的毛发及饭粒的混合物放入锥形瓶中，向瓶中加入20g疏通剂和100mL水。反应时瓶内物上下翻动明显、有大量气体产生、放热，反应后发现饭粒成粥状，毛发小部分消失，用玻璃棒挤压，头发容易压断变成碎屑。

【实验启示】气体能起物理松动效果；“毛发部分消失易断裂”说明疏通剂具有____性；实验中产生的气体仅是水蒸气吗？小科查资料明白气体中还含有氢气：铝与氢氧化钠溶液反应时放出大量的热，反应方程式为：2Al+2NaOH+2H₂O=2NaAlO₂+3H₂↑。

【提出问题】疏通剂在使用时遇到明火，氢气会被点燃吗？

【实验二】小科取两只250 mL锥形瓶，分别加入“妙管家”和“花仙子”50g、水150mL 。过程中用燃着的木条点燃产生的气体，“妙管家”产生的气体可以被点燃，而“花仙子”产生的气体未被点燃。

【实验猜想】“花仙子”产生的气体未被点燃的原因？

猜想一：____导致了“花仙子”产生的气体中氢气的量较少；

猜想二：反应中有大量的热产生，导致产生的气体中混有大量的水蒸气。

【实验设计】能否让“花仙子”产生的气体被点燃？

热的水蒸气遇冷会____（填物态变化名称），小科依据猜想二设计了用浓硫酸和冷的蒸馏水来处理水蒸气的两种实验方案；实验前，为安全考虑，小科请老师对方案进行审查。若你是指导老师，你会选择方案____来完成实验。通过实验，小科认为，管道疏通剂疏通效果好，但存在着安全隐患，应要有更好的产品替代。

生活中的下列现象，可用分子的知识加以解释，其中正确的是