问题补充：
Quzhou is a beautiful city. Every year there are tourists.
A. thousands
B. thousands of
C. thousand
D. thousand of
答案：
A. thousands
(答案→)B. thousands of
C. thousand
D. thousand of
解析：句意：衢州是一个漂亮的城市，每年都有数千名游客。表示不确定所指时用thousands of的形式，确定所指不加s,不加of,故选B
