人的主要组织相容性抗原为() A.HLA B.LA C.H-2 D.AgBH-1 E

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问题:

人的主要组织相容性抗原为()

A.HLA

B.LA

C.H-2

D.AgBH-1

E.RLA

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为什么说赵树理的小说表现出一种极具个性的“细节的现实主义”特点?

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As the railroads and the highways shaped the American West in the past centuries, a new electhical generating(发电)and transmission(输送)systen for the 21th century will leave a lasting mark on the West, for better or worse. Much of the real significance of railroads and highways is not in their direct physical effect on the scenery, but in the ways that they affect the suurouding community. The same is true of big solar ppants and the power lines that will be laid dowm to move electricity around.

The 19th century saw land grants(政府拨地)offered to railroad companies to build the transcontinental railroads ,leaving public land in between privately owned land . In much of the west ,some of the railroad sections were developed while others remained undeveloped ,and in both cases the landownership has presented unique challenges to land management ,with the completion or the interstate highway system ,many of the small towns which sprang up as railway stops and developed well ,have lost their lifeblood and died .

Big solar plants and their power lines will also have effects far beyond their direct footprint in the west .this is not an argument against building then ,we need alternative energy badly .and to really take advantage of it we need to be able to move electricity around far more readily than we can now .

So trade-offs will have to be made .some scenic sport will be sacrificed .some species (物种)will be forced to move ,or will be carefully moved to special accommodations ,deals will be struck to reduce the immediate effects .

The lasting effects of these trade-offs are another matter .the 21st century development of the American west as an ideal place for alternative energy is going to throw off a lot of power and money to do a lot of good .but it is just as likely that they will be spent wastefully and will leave new problems behind ,just like the railroad and the highway .

The money set aside in negotiated trade –offs and the institution that control  will shape the west far beyond the immediate footprint of power plants and transmission lines .so let’s remember the effects of the railroad and the highways as we construct these new power plants in the west .

小题1:

what was the problem caused by the construction of the railways ?

A.small towns along the railways became abandoned .

B.some railroad stops remained .

C.land in the west was hard to manage .

D.land grants went into private hands.小题2:

what is the major concern in the development of alternative energy according to the last two paragraphs ?

A.the transmission of power

B.the use of money and power

C.the conservation of solar energy

D.the selection of an ideal place小题3:

what is the author ‘s attitude towards building solar plants ?

A.cautious

B.approving

C.doubtful

D.disapproving小题4:

which is the best title for the passage ?

A.how the railways have affected the west

B.how solar energy could reshape the west

C.how the effects of power plants can be reduced

D.how the problems of the highways have been settled

题型:单项选择题

土壤蔗糖酶 soil saccharase

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在已经建立的“工资库”中,要在表中直接显示出我们想要看的记录,凡是姓“李”的记录,可用()的方法。

A.排序

B.筛选

C.隐藏

D.冻结

题型:单项选择题

水中某些污染物可通过水中______的生物放大作用,使生物体内含量大大高于水体中浓度

A.水生生物

B.食物链

C.生物转化

D.生物迁移

E.氧化还原反应

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