Mary with two cats_____in the yard when Wenchuan earthquake happened.A.is playing B.was playing C.a
问题描述：
Mary with two cats_____in the yard when Wenchuan earthquake happened.A.is playing B.was playing C.a
答
B
看with最前面的人称选择单复数,因此mary是第三人称单数
由于后面的happend,所以是过去式
综上,选b