问题补充:
Mary by the lake when a black cat ran past her.
A. sat
B. has sat
C. was sitting
D. sits
答案:
A. sat
B. has sat
(答案→)C. was sitting
D. sits
解析:此题重点考查过去进行时的基本用法,表示在过去某个时刻正在进行的动作或存在的某种状态。根据语境可知此句的含义一只黑猫跑过其身边的时候Mary正坐在小湖边。故用过去进行时。过去进行时的基本构成是was或were+ving,故选C。