Mary by the lake when a black cat ran past her.A. satB. has satC. was sittingD. sits

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。