问题
选择题
动物体内甲种氨基酸通过转氨基作用生成乙种氨基酸，可以肯定的是[ ]
A．甲种氨基酸是必需氧某酸
B．甲种氨基酸是非必需氨基酸
C．乙种氨基酸是必需氨基酸
D．乙种氨基酸是非必需氨基酸
答案
答案：D
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动物体内甲种氨基酸通过转氨基作用生成乙种氨基酸，可以肯定的是[ ]
A．甲种氨基酸是必需氧某酸
B．甲种氨基酸是非必需氨基酸
C．乙种氨基酸是必需氨基酸
D．乙种氨基酸是非必需氨基酸
答案：D
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| Huandreds of years ago, life was 1 than 2 today. People didn't have modern machines. There 3 modern medicine, either. Life today 4 new problems. One of the biggest is pollution. Water pollution has 5 our rivers and lakes dirty. It kills our fish and affects our drinking water. Noise pollution makes us 6 louder and 7 . Air pollution is the most serious kind of pollution. It affects every living thing in the world. Cars, planes and factories all pollute our air every day.Sometimes the pollution is so 8 that it is like a quilt (被子) 9 a city. This kind of quilt 10 smog (雾). Many countries are making new laws to fight pollution. Factories must now clean their water 11 away. They mustn't blow dirty smoke into the air. We need to do many other things.We can put a waste thing in the dustbin and not throw it on the ground. we can go to work by bus 12 with our friends 13 . If there are fewer people driving, there will be 14 pollution. Laws are not 15 . Every person must help to fight pollution. |
| ( )1.A.more hard ( )2.A.they are ( )3.A.were not ( )4.A. bring ( )5.A.made ( )6.A.say ( )7.A.felt happy more quickly B.get angry much easier C.become angry more easily D.feel sad more slowly ( )8.A. thin ( )9.A.around ( )10.A.calls ( )11.A.before they are thrown B.when they are thrown C.after it is thrown D.before it is thrown ( )12.A.and ( )13.A.in the same car ( )14.A.little ( )15.A.enough | B. more harder B.they were B.was no B.have B.let B.talk B.thick B.on B.is seen B.or B.go to our office B.less B.good enough | C. much harder C.it was C.were C.have got C.taken C.tall C.hard C.in C.is called C.but C.in different cars C.much C.enough good | D.much more harder D.it is D.was D.has brought D.changed D.spoke D.light D.over D.is like D.if D.go home D.more D.good |