写出下列动词的第三人称单数形式、现在分词和过去式答:5 helps, helped, helped 6 eats, ate, eaten 7 sees, saw, saw 8 affords, afforded, afforded 9 sells, sold, sold 10 finds, found, found 11 thinks, thought, thought 12 learns, learned/learnt, learned/learnt 13 joins, joined, joined 14 dances, danced, danced 15 swims, swam,...