1. were→are 2. reason→reasons 3. useless→useful 4. 去掉stay前的 to 5. worried后加about
6. a→the 7. many→more 8. we→they 9. prevent前加to 10. leave→leaving
1. were→are 2. reason→reasons 3. useless→useful 4. 去掉stay前的 to 5. worried后加about
6. a→the 7. many→more 8. we→they 9. prevent前加to 10. leave→leaving