We will have no water to drink unless we learn to save water.(保持句意不变)

问题描述:

We will have no water to drink unless we learn to save water.(保持句意不变)
We will have no water to drink _____we ____learn to save water.

We will have no water to drink __if ___we __don't__learn to save water.
意思是 如果我们不懂得节约用水的话 我们将没有水可以喝