▲閱讀下文，回答第 46-50 題
        Sam and his father were about to build a doghouse for their puppy, Lucky. Sam wantedLucky to have a place to stay dry when it rained and stay cool when it was hot. Sam and his dadhad gone to a store to get their supplies, and now they were ready to begin the project. Sam’sdad explained that the first thing they would need to do would be to measure Lucky.
        After they measured Lucky, it was time to build the frame. Sam and his dad used strongboards for the frame, so the doghouse would be sturdy. Then, they measured and cut plywoodfor the walls and floor. They also made sure to cut an opening that was big enough for Lucky togo in and out. Once they attached it to the frame, it was time to start working on the roof.
        Sam and his dad started with strong boards for the roof frame, and then they used otherboards for the rafters. They used plywood to complete the shape of the roof. The roof wouldneed to protect Lucky from rain and too much sun, so they also put shingles on the roof. Samthought the doghouse roof looked a lot like the roof of his own house. His dad explained that thepitched roof would help the rain fall off the roof instead of collecting on top of it.
       Finally, the doghouse was ready to be decorated. Sam painted it bright red, and paintedLucky’s name above the door. As a finishing touch, Sam put a carpet and a blanket in thedoghouse. Lucky was going to be a comfortable puppy! Sam could not believe how good thedoghouse looked. He was glad that he had thought of this idea.
【題組】46. What is the main idea of the passage?
(A) The steps of building a doghouse.
(B) The space a dog needs to move around.
(C) The materials needed to build a doghouse.
(D) The idea of living comfortably with a dog.