There is some rubbish under the tree.We can't sit under the tree.（合并句子）

There is some rubbish under the tree.We can't sit under the tree.（合并句子）
There is some rubbish under the tree.We can't sit under the tree.（合并句子）

There is some rubbish under the tree.We can't sit under the tree.（合并句子）
Because there is some rubbish under the tree,we can't sit under the tree

There is some rubbish under the tree under which we can't sit.

There is so much rubbish under the tree that we can't sit under the tree.

There is some rubbish under the tree so we can't sit there

这里有一些兔子在树下面。我不能坐在树下面