问题补充：
A number of foreign visitors Chengdu many times because it is such a beautiful city.
A. have been to
B. has been to
C. has gone to
D. have gone to
答案：
(答案→)A. have been to
B. has been to
C. has gone to
D. have gone to
解析：句意：因为成都是一个美丽的城市，所以有许多外国人已经参观了多次。分析句意体现了现在完成时，许多外国人已经来过成都用have been to (曾经去过某地),同时a number of 同义于a lot of，因此主语可数名词复数，助动词用have,故选A
