表示变化
1)Some changes have taken place in the past five years.
2)A great change will certainly be produced in the world’scommunications.
3)The computer has brought about many changes in education.
例如：
Some changes have taken place in people’s diet in the past five years. The major reasons for these changes are not far to seek. Nowadays，more and more people are switching from grain to meat for protein，and from fruit and vegetable to milk for vitamins.
