学进去

   One day a pig went to the stable (马棚) to ________ a good friend, an old horse. He was going to ________ there for the night. Night came and it was time ________ sleep. The pig went into the straw heap (稻草堆) and lay comfortably (舒服地). A long time ________, but the horse was still ________ there and did not move. So the pig asked the horse ________ he did not go to sleep. “Standing like this is the beginning of sleeping.” answered the ________. The pig found it ________ to believe (相信) and said, “How can you stand there sleeping? It is not comfortable at all.” The horse answered, “Comfort (舒适) is your habit . As horses, we have the habit of running ________. So we are always ready ________ quickly even if (即使) we are asleep (睡着).