问题
选择题
Mr. Smith, who often helped passers-by repair their bikes, said that what he did was not paid but _______.
A．relevant
B．optional
C．suitable
D．voluntary
答案
答案：D
题目分析：考查形容词辨析。句意：史密斯先生，经常帮助行人修理自行车，他说他做的事情不要报酬，是自愿的。A相关的；B可选择的；C合适的；D志愿的，无偿的。not...but...不是......，而是......，故选D。