These big trees saved the elephants and we can't cut down them.
We can't cut down the trees because they saved the elephants.
The trees are not allowed to be cut down because they saved the elephants.
可能会被说前后时态不一致，但是我觉得说得通，树救大象发生在以前，所以现在我们不许砍树。。
These big trees saved the elephants and we can't cut down them.
We can't cut down the trees because they saved the elephants.
The trees are not allowed to be cut down because they saved the elephants.
可能会被说前后时态不一致，但是我觉得说得通，树救大象发生在以前，所以现在我们不许砍树。。