用所给词的正确形式填空。 1.They visited “The World of Robots” on the __________ (two) floor. 2.Alice is good at dancing. She is a good __________ (dance). 3.Peter __________ (buy) a model plane yesterday. 4.He __________ (can) eat five hamburgers a day ten years ago. 5.Horses can run very __________ (fast).