Ⅰ.单词拼写
1．The author________(后悔)having ignored his friend’s warning.
答案：regretted
2．Researchers have been________(对……感到困惑)how to prevent disasters.
答案：confused
3．Exercise is a great way to________(减少)pressure.
答案：reduce
4．My teacher made a________(评论)about my mistake.
答案：comment
5．The special________(化学物质)to clean your house may have a bad effect on your health.
