第Ⅰ卷（选择题）
Ⅱ.单项填空(共15小题；每小题1分，满分15分)
21.The possibility________ pleasant smells might reduce pain has been suggested by new research.
A. that B. which C. what D. when
【解析】选A。句意：令人舒服的气味可以减轻疼痛，这种可能
性已被新的研究揭示。possibility为先行词，由that引导同位语从
句，对possibility起解释说明的作用。
