you have a rich knowledge of Chinese history, try acting as a guide for these foreign visitors.
A. Unless
B. Though
C. Now that
D. Ever since
网友回答
A. Unless
B. Though
(答案→)C. Now that
D. Ever since
解析：句意：既然你有丰富的中国历史知识，那就试着担当这些外国游客的导游。A. Unless 除非，如果不；B. Though 尽管，虽然；C. Now that既然，由于；D. Ever since自从。根据句意可知选Ｃ。