I think he’s been drinking I’m not completely sure.A. ifB. thoughC. untilD. as

问题补充：

I think he’s been drinking, I’m not completely sure.

A. if

B. though

C. until

D. as

答案：

A. if

(答案→)B. though

C. until

D. as

解析：if “如果、是否”；though “虽然；尽管”；until是“直到……才……”；as “由于、因为”。由上句“我认为他一直饮酒”和下句“我不能完全确定”可知，两者是让步关系，用though引导让步状语从句。句意为“我认为他一直在饮酒，尽管我不恩给你完全确定。

【考点】考查连词意义辨析。