单选题 Health care workers should always explain the ______ effects of physical exercise to their patients.
A. benefiting
B. benefits
C. beneficiary
D. beneficial

【正确答案】 D
【答案解析】选项(D)beneficial(有益的)是形容词，可用于修饰effects。选项(A)benefiting是现在进行时形式。选项(B)benefits是名词复数形式或动词第三人称单数形式。选项(C)beneficiary是名词，意思为“受益者”。