大学英语：on the average

5. on the average

　　On the average， girls score higher on tests that measure vocabulary， spelling， and memory.

　　We made 65 miles an hour on the average.

　　6. be determined by

　　People's abilities are not determined by sex.

　　The rise and fall of the prices is determined by supply and demand.

　　7. be headed by

　　One of the scientific research teams was headed by Mr. Watson.

　　This company is headed by John's twin brother.

　　8. be ready to

　　He is always ready to help people in need.

　　She is not ready to take on that kind of responsibility.