错例:Oneof the most challenging problem is who should be responsible for looking after the elderly people.

正解:Oneof the most challenging problems is who should be responsible for looking after the elderly people.
改错练习:
1. What our modernsociety values are the personality and creativity.
2. Private car willexert adverse impacts on the environment and traffic of the whole society.
3. Long-distance education provides students interesting way to learn.