问题
选择题
在做蚯蚓的有关实验时，“蚯蚓怕干”的原因是它的呼吸是靠（ ）
A．肺
B．气管
C．体壁
D．鳃
答案
蚯蚓的体壁密布毛细血管，土壤中的氧气先溶解在体表的黏液里，然后渗进体壁，再进入体壁的毛细血管中．体内的二氧化碳也经体壁的毛细血管由体表排出，蚯蚓的呼吸要靠能分泌黏液、始终保持湿润的体壁来完成．
故选：C
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在做蚯蚓的有关实验时，“蚯蚓怕干”的原因是它的呼吸是靠（ ）
A．肺
B．气管
C．体壁
D．鳃
蚯蚓的体壁密布毛细血管，土壤中的氧气先溶解在体表的黏液里，然后渗进体壁，再进入体壁的毛细血管中．体内的二氧化碳也经体壁的毛细血管由体表排出，蚯蚓的呼吸要靠能分泌黏液、始终保持湿润的体壁来完成．
故选：C
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| Is the world really going mad? 1 day I was sitting in a restaurant 2 a quick and a talk with a few friends when it suddenly 3 me that almost everyone in the restaurant was smoking. It wasn't long 4 the whole room was 5 with smoke. I asked with an apology for 6 to open a window to stop myself 7 ! Nowadays air pollution is something that is hardly questioned any more. However, I stil  l can't walk down the street in any of the big cities without 8 that people are 9 the air pollution. It is time for the government departments of the world to introduce emission(废气排放) controls on all cars and 10 the public transport system(公共交通体系) to encourage people to 1 their cars at home. A friend of mine takes flying lesson each morning and it really makes him 12 when he climbs above the smog layer(烟 雾) and looks down 13 it and thinks: "I'm breathing that!" this kind of 14 results from the bad management of resources. Waste things can 15 should be treated properly. House building, road 16 , and industrial development are all earthmoving( or earth-reducing) operations and can change the balances of 17 created over millions of years. I would like to 18 serious studies done on all these main works before they are built. Also, there should be 19 national parks set up to keep the most beautiful parts of our countries in their natural 20 . | ||||
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