Results of a recent study appear to explain the long-standing question of why many women develop lung cancer, ______ they themselves are non-smokers. A.if B.unless C.but D.although
A.A.if B.unless C.but
【参考答案】
D 解析：句意：一份最近的研究结果好像解释了长期以来的一个问题，即为什么许多女人会得肺癌尽管她们自己并不吸烟。本......