第18题: [单项选择]I had just stepped out of the bathroom and was busily drying myself with a towel ______ I heard the steps. A. while B. when C. since D. after 参考答案:B 答案解析:[考点] 状语从句 [解析] when既可表示某一点时间,也可以表示某一段时间。在when引导的时间状语从句中,其谓语动词既可以是延续性的,也可以是非延续性的,可与主句中的谓语动词同时发生,