It took me two hours to finish my homework. I spent two hours on my homework.(词组:spend st on sth.) I spent two hours in finishing my homework.(词组:spend st in doing sth.) 所以50844805那位的第二句是错的, memoriestree 那位的也是错的. KTBL_Johnluck这位的两句都是错的. qiqiesp 这位的第三句是错的,第一句也不对,cost主要是用于钱的. 请相信我,全班英语第一哦