单选题 John doesn't believe in ______ medicine; he has some remedies of his own.
A. standard B. regular C. routine D. conventional

【正确答案】 D
【答案解析】standard意为“标准的，权威的”，指公认为权威或优秀的；regular意为“定期的，固定的”；routine意为“例行的，习惯性的”，指没有特征的；conventional意为“传统的，习俗的”，指遵循被确定的惯例或者被认可的准则的。所填之词修饰 medicine，根据后面的he has some remedies of his own可知，应选conventional。