将△ABC的三个顶点的横坐标不变，纵坐标乘以﹣1，则所得图形（　　）

人们看到美国有大量的黑人，他们有的是非洲的移民，有的是非洲的移民后裔。那么，在美国最早大量出现黑人是由于（    ）

短文改错。

Dear Jim,

    I'd like to tell you something more about our school sports meet. It was holding on Oct. 6th, it was a fine day. There were over 1,000 students and teachers attended it. Wang Lin, a student from my class won the 100-meters race. He finished the race in 12.6 seconds and broke the school record. The sports meet was really success. That was because we were all trying to do my best. Although I was not one of the winner, I was proud of that we had done.

    Looking forward to receive your letter.

Yours,

 Li Ping