根据短文内容，填写所缺单词或用括号中所给单词的正确形式填空，使短文意思完整。
We all know that nature is important to us, but do we really know how to live in harmony 1. it?
Last month, our school organized a tree-planting activity. We saw 2. the hill we went to was once almost empty. So each student planted at least one tree. It was hard work, but when we saw the young trees 3. (stand) straight in the wind, we felt really proud.
Our science teacher also told us that trees can help 4. (reduce) air pollution. They take in 5. (harm) gases and produce oxygen, which makes the air cleaner. Besides planting trees, we should also try 6. (save) water in our daily life. For example, turn off the tap while 7. (brush) our teeth, and take shorter showers.
Sadly, many animals are in danger now because their homes 8. (destroy) by humans. We must do something 9. (protect) them. If we continue to care for our planet, it 10. (become) a better home for all living things.

1. with 2. that 3. standing 4. reduce/to reduce 5. harmful 6. to save 7. brushing 8. have been destroyed/are destroyed 9. to protect 10. will become

1. 考查固定搭配in harmony with，意为“与……和谐共处”，故填with。
2. 考查宾语从句引导词，此处saw后接的宾语从句语义完整、不缺句子成分，用that引导，that无实际语义，故填that。
3. 考查非谓语动词，固定结构see sth. doing sth. 表示“看见某物正在做某事”，用现在分词作宾语补足语，体现小树苗正挺立在风中的状态，故填standing。
4. 考查固定搭配help (to) do sth.，意为“帮助做某事”，故填reduce/to reduce。
5. 考查词性转换，此处修饰名词gases需要使用形容词，harm的形容词形式harmful意为“有害的”，harmful gases表示有害气体，故填harmful。
6. 考查固定搭配try to do sth.，意为“尽力做某事”，故填to save。
7. 考查状语从句的省略，while引导时间状语从句时，当从句主语和主句主语一致，且从句谓语包含be动词，可省略主语和be动词，此处主语we和brush是主动关系，故填现在分词brushing。
8. 考查被动语态，主语their homes和动词destroy是动宾关系，结合语境可知动物的家园已经被人类破坏，用现在完成时的被动语态，主语为复数，故填have been destroyed，也可使用一般现在时被动are destroyed。
9. 考查非谓语动词，此处用不定式作目的状语，表示“做一些事来保护它们”，故填to protect。
10. 考查动词时态，if引导的条件状语从句遵循“主将从现”规则，从句用一般现在时，主句要使用一般将来时，故填will become。