20.Why were all the horses outside at the house door?

A.Because someone drove them out of the house.

B.Because the smell in the big house was really terrible.

C.Because the horses didn’t like to stay with people at night.

第一节 单项选择（共15小题，计15分）

       从每小题A、B、C、D中选出一个能填入句中空白处的最佳答案。