Do you know anything about water? You may say, "I 1．water every day." When you look at the map of the 2．, you can find there is more water than land. But the water in the 3．is salty. We can't drink this salty water. There are also a lot of very small 4．things in the sea. They live with fish and 5．.
What do you know about fire? Fire is useful(有用的).With fire people can1．food, warm themselves and frighten(使惊吓)animals, But fire can be very dangerous too. For example, it can 2．down buildings and forests. So we must be 3．with fire. We mustn't 4．near fire and we mustn't play with5．.
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