I'm mistaken I've seen that tall man at a party before.A. IfB. AsC. UnlessD. When

问题补充：

Im mistaken, Ive seen that tall man at a party before.

A. If

B. As

C. Unless

D. When

答案：

A. If

B. As

(答案→)C. Unless

D. When

解析：C 考察连词辨析。If如果，as因为；unless除非，如果不；when当…时；句义：如果没有错，我以前在晚会上遇见过那个高个子的男人。故C正确。