问题
选择题
If you want to see a doctor, fix the date with him ahead of time. This is a common ___________ in the USA.
A. habit B. law C. rule D. custom
答案
答案：D
本题是典型的词语辨析题，habit通常为“生活习惯”，law为“法律”，rule为“条文规定”，custom为“习惯”，所以D项符合题意。