Ⅰ. 根据句意及首字母提示完成单词(10分)
1. It is said that colors can i _____our feelings.
2. It’s our d _____ to protect the environment.
3. No matter how hard it is, we must f_____ it bravely.
4. If you quarrel with your friend, your friendship may be l_____.
5. The population of the world has reached 7 billion, so the increasing(增长)population may be the greatest c_____ of the world today.