$tree=$a与$tree[]=$a 有啥区别

In a tree on a tree区别 A tree,Trees ,The tree,有什么区别, in the tree和in a tree 有区别吗 a leaf on a tree和a leaf from a tree有什么区别 in a/the tree和 up a/the tree 有什么区别. in the tree和in a tree有区别吗?哪个是对的 climb the tree 或climb a tree 哪个正确?有什么区别 a young apple tree 一个英语的完成时问题there has a tree 和 there has been a tree 两者有什么区别?还 in the tree ,与on the tree区别 there is a tree in the garden与there is one tree in the garde There is a tree in the garden.与There is one tree in the gard