第1个回答 2007-04-07
i am sitting under a tree (现在进行时)
I was sitting under a tree (过去进行时)
第2个回答 2007-04-07
I am sitting under a tree.
第3个回答 2007-04-07
I am sitting under the tree本回答被提问者采纳
第4个回答 2007-04-07
i'm sitting under the tree.
第5个回答 2007-04-07
i am sitting under a tree.