填空，完成对话。— Where does the rain come from?
— It comes from the _________________.
— Where does the cloud come from?
— It comes from the _________________.
— Where does the vapour come from?
— It comes from the_________________ in the river.
— How can the water become vapour?
— The _________________ shines and the water becomes _________________. clouds; vapour; water; sun; vapour