问题
解答题
已知xm=3，xn=5，求x2m+n的值．
答案
原式=（xm）2•xn
=32×5
=9×5
=45．
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已知xm=3，xn=5，求x2m+n的值．
原式=（xm）2•xn
=32×5
=9×5
=45．
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| Hundreds of years ago, life was much harder than it is today. People didn't have medicine. There was no modern machine, 1_______. Life today has brought new problems. One of the biggest is 2_______. Water pollution has 3_______ our rivers and lakes dirty. It kills our fish and 4_______ our drinking water. Noise pollution makes us 5_______ louder and become angry more easily. Air pollution is the most 6_______ kind of pollution. It's 7_______ to all living things in the world. Cars, planes and factories all pollute our 8_______ every day. Sometimes the polluted air is 9_______ thick that it is like a quilt (被子) called smog (烟雾). Many countries are 10_______ rules to fight pollution. Factories must now clean their water 11_______ it is thrown away, and they mustn't let dirty 12_______ go into the air. We need to do many other things. We can put waste things in the 13_______ and do not throw them on the ground. We can go to work by bus 14_______ our friends in the same one. If there are fewer people driving, there will be 15_______ pollution. Rules are not enough. Every person must help to fight pollution. | ||||
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