第1个回答 2012-12-05
He spent an hour solving this difficult problem.
或：He took an hour to solve this difficult problem.
以上两种都可以。
希望可以帮到你，如果不懂可追问，望采纳！
第2个回答 2012-12-05
He spent an hour resolvingthe differcult problem
如果帮到你，请记得采纳，O(∩_∩)O谢谢
第3个回答 2012-12-05
He spent 1 hour explain the difficult problem.本回答被提问者采纳
第4个回答 2012-12-05
He spent one hour working out the difficult problem.
第5个回答 2012-12-05
He spent 1 hour to explain the difficult problem。