Mr. Black has two cats(猫). One is big(大的) and the other is small（小的）. He likes them very much. One day his friend Mr. Green comes to see him. He is surprised(惊奇). He find there are two holes(洞) in the door, a big and a small one. He says, “My dear friend, why are there two holes in your door?” “To let them in or out,” Mr. Black answers. “But why are there two holes?” asks his friend. “ How can the big cat go through（通过）the small hole?” he says.
Mr. Black has ____________.
A. two small cats
B. two big cats
C. a big and a small cats
Mr. Green comes to see___________.
A. Mr. Black               B. the cats            C. the holes
Mr. Black wants _____________ to go through the two holes.
A. the big cat               B. the small cat       C. the two cats
Mr. Black thinks the big hole is only for the____________.
A. the big cat               B. the small cat        C. Mr. Green
____________ is not necessary（必要的）.
A. The big hole             B. The small hole      C. The door