题目

Everybody hates rats．But in the earthquake capitals of the world-Japan，Los Angeles，Turkey-rats will soon be man's new best friends． What happens after an earthquake? We send in rescue dogs．Why? Because they can smell people．Dogs save lives．They help rescuers to find living people．But dogs are big hand they can't get into small spaces．So now a new research project is using a smaller animal to save lives：the rat． How does it work? First，the rat is trained to smell people．When this happens，the rat's brain gives a signal（信号）．This is sent to a small radio on itOur house is big, but ________ is much bigger than ________.A.their…ourB.their…oursC.theirs…ourD.theirs…ours