在discussion中有一个复选框是 “I am asking a question and want to get answers from other members. ”这个选了不选有什么区别嘛？我试验了几次~感觉没有什么大的区别啊~还有~这个有时效性嘛？就是我提问完了以后~需要回复~有没有要求多长时间内他需要回复？如果没回复会怎么样呢？谢谢~
------解决思路----------------------
"The "I am asking a question and want to get answers from other members" check box can be used to tell if your new discussion is a question or just discussion.
After checking it, you and other users will see the questions under Unanswered questions. With this, other users will easily find which are questions so that they can help to answser it."
参考：http://community.office365.com/themes/groups/generic/forums/thread.aspx?ForumID=148&ForumThreadID=239020&GroupKeys=en-us/
另外，既然是一个unanswered question应该是没有时效性的。