问题补充：
the tourists come from South Korea.
A. Three hundred
B. Hundreds of
C. Hundred of
D. Three hundred of
答案：
A. Three hundred
B. Hundreds of
C. Hundred of
(答案→)D. Three hundred of
解析：
试题分析: 句意：金鱼非常缓慢地游动，睡多了。three hundred 三百，three hundred of……中的三百个，
后接名词， hundreds of成百上千的，后接名词，故选D.
