阅读理解 Below is a summary of some of the main points of the passage. Read the summary and then select the best word or phrase from the box below, according to the passage. You should decide on the best choice and mark the corresponding letter on the ANSWER SHEET with a single line through the center.

填空题 17.【R1】

填空题 18.【R2】

填空题 19.【R3】

填空题 20.【R4】

填空题 21.【R5】

填空题 22.【R6】

填空题 23.【R7】

填空题 24.【R8】