问题补充：
—I think you can’t believe I had to pay $20a haircut?
—You should try the barber’s I go. It’s only $5.
A. off; a
B. for; which
C. for; where
D. for; that
答案：
A. off; a
B. for; which
(答案→)C. for; where
D. for; that
解析：考查固定搭配和从句，pay for意思“为……付钱”，从句I go不缺少成份，所以用where，句子意思“我认为你不会相信我剪头发花了20，你应该试一下我去的那个理发店，仅花5元”，所以选C
