根据句意和中文意思，写出单词的正确形式。

1. The red lines on the map often _____(代表) railways．

2. Planting trees can help to make our _____(环境) clearer and more beautiful.  

3. Sometimes it’s difficult for us to make _____ alone.(决定)

4. Seven _____of the trees have been watered so far.(二十)

5. He likes to wear yellow coats, because yellow is the colour of _____. (智慧)