问题
选择题
下列物质中，属于氧化物的是
A．氧气
B．水
C．高锰酸钾
D．氢氧化钠
答案
答案：B
题目分析：由两种元素组成的化合物，其中一种是氧元素属氧化物。氧气属单质；水属氧化物；高锰酸钾属化合物；氢氧化钠属化合物。故选B。
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下列物质中，属于氧化物的是
A．氧气
B．水
C．高锰酸钾
D．氢氧化钠
答案：B
题目分析：由两种元素组成的化合物，其中一种是氧元素属氧化物。氧气属单质；水属氧化物；高锰酸钾属化合物；氢氧化钠属化合物。故选B。
阅读下面的短文，根据短文中的信息完成文后的表格（每空一词） Do you know how to keep fish at home? The fish need room(空间). They must not be crowded（拥挤）. Fish need oxygen(氧气). Fish get it from water in the tank. There must be enough water for all fish in the tank. So the size of the tank is important.. In the tank many people put small plants. They give oxygen to the water. Plants help in other ways, too. Fish can nibble(轻咬)on the plants. They hide in the plants and sleep, lay eggs there. Both the plants and fish need light. You can put it near a window. It will get light there. But remember: a window may let cold air in. The cold can kill(杀死) your fish. Too hot water can kill your fish, too. The fish need food and you should feed them every day. Giving them too much food is bad. It will make the water dirty. However, the fish should get just enough food. They should finish the food in 10 minutes. No extra(多余) is left. When this happens, the amount(数量)of food is right. How to keep fish at home
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