— How’s your tour around the North Lake? Is it beautiful?
— It be, but it is now heavily polluted.
A. will
B. would
C. should
D. must
网友回答
A. will
B. would
(答案→)C. should
D. must
解析：句意：--你去the North Lake 的旅行怎么样，漂亮吗？---the North Lake应该是很美的一个湖泊，但现在被污染了，言外之意，这个湖泊之美要打上问号。Should这个情态动词有“按理推测”的含义，可译成“理应……”等含义，符合对话的真实意图。答语如果用It should have been, but…也是可以的。will表“现在的自然倾向”，would表“过去习惯、倾向”，must 表“肯定推测”，均不符句意。选C。