這句話為什么用過去時
新目標9年級第十四單元的一篇文章,He's already visited the place where his ancestores lived.通篇都用的現(xiàn)在完成時和一般現(xiàn)在時（只有講到“祖先”們怎樣怎樣時才用一般過去時）,可在倒數(shù)第二段插了一句一般過去時,而且不是講“祖先”的,我很不理解,整篇文章如下：
Have you been back to the place where your ancestors lived,worked,studied and played?Robert Qian,a Chinese Canadian,already has.Now in China,he has found that his family is like a tall tree with long roots.
Robert is just one young overseas Chinese who has come to visit his ancestors' homeland,as part of the In Search of Roots summer camp program.The program is organized by the local government of Guangdong Province.This program started in 1980,and so far has brought thousands of overseas Chinese students to China to look for their families' roots.The young people are usually between 16 and 25 years old.Most,like Robert,can hardly speak any Chinese,and have never been to China before.
The students mainly visit parts of Guangdong Province in southern China.During the two-week camp,they study Chinese culture,see changes that have happened in that area,and visit interesting sights.Going to their ancestors' village is often the most exciting part of the trip.The students feel that they are part of the village,and experience village life.They drink from the village well,go for walks through the countryside,and watch the villagers do their daily activities.
Cathy Qin,a young American student,had（我說的就是這個過去式had） this to say,"Thanks to In Search of Roots,I am beginning to understand my Chinese roots,and who I am.It has been a great trip,and I have so many memories of China to take with me."
The program leaders believe strongly in the program and say that the purpose of it is to give young overseas Chinese the chance to learn more about themselves."I've really enjoyed the trip so far," says Robert."This has been a big step for me,and I'm looking foreard to finding out more about my roots during my time here."