问题
选择题
在一个农田生态系统中，若含有DDT，经过一段时间，以下生物体内的DDT浓度最高的是 [ ]
A．禾谷类
B．昆虫
C．食虫鸟
D．鹰
答案
答案：D
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在一个农田生态系统中，若含有DDT，经过一段时间，以下生物体内的DDT浓度最高的是 [ ]
A．禾谷类
B．昆虫
C．食虫鸟
D．鹰
答案：D
| 完形填空。 | |||
| We can use many kinds of energy. Most energy in the l today comes from 2 coal and oil. But this will not be so in the year 2050. We will get much of our energy _ 3 water, the sun and the 4 .We will produce atomic(原子) energy, much more coal and 5 as raw material（原始材料）for cloth, plastics and other things. Some 6 of the world are very dry. Very __7_ people live there, 8 there is a lot of sunshine and wind. With 9 atomic energy and energy from the sun and wind, we will be able to bring fresh water from far away or change sea water 10 fresh water. | |||
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