It was Saturday, so Mr. Smith did not have to go to work. It had snowed heavily the night before, and Mr. Smith's son Bobby had a new sledge  , which he had been very eager to try out for a long while. There was a good slope   in a park not far away from the Smiths' house -- a slope which children often used for their sledges, so Mr. Smith agreed to take Bobby there in the car. They put the sledge in and went off.  When they reached the park, they found that there were already a lot of boys there, each boy with a sledge of his own. They were sliding down the slope at great speed, and then pulling their sledges up again for another go.  Mr. Smith stood by, watching them with a smile. It was obvious that each and every one of them had much fun. After a few moments, Mr. Smith suddenly saw among the boys a kid who was small and poorly-dressed, and did not have a sledge. This boy had flattened out one old cardboard box, and was sliding down the slope on that. Mr. Smith felt very sorry for this poor boy, and determined to tell his son Bobby to share his new sledge with the boy.  But before he could catch Bobby to speak to him, he was somewhat surprised -- and much more delighted -- to notice that several of the older boys in the park were already offering the poor boy their nice sledges. Mr. Smith watched them with greater interest -- and suddenly realized that the bigger boys were not doing this because they felt sorry for the poor boy, but because they enjoyed riding on his cardboard box more than on their own sledges. They were actually waiting eagerly and impatiently for a turn on the flattened cardboard box! Mr. Smith was very pleased before speaking to his son because   _  .
the bigger boys enjoyed riding on their sledges more than on the box the small and poor boy had already got a new sledge from his parents all the boys were sharing the flattened cardboard box in turns politely some of the bigger boys had already offered their sledges to the poor boy