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【单选题】
什么是氮素循环中的固氮作用:A.
土壤或水体中的氨态氮经化能自养菌的氧化而成为硝酸态氮的过程
B.
大气中的氮气通过某些原核微生物合称为化合态氮
C.
有机氮经过微生物的氨化作用释放出氨
D.
硝酸和亚硝酸在无氧条件下经微生物的反硝化作用，最终变成氮气或气态氮化物，返回至大气中
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举一反三
【单选题】I regretted not having finished my composition last night, I to the cinema with Mary.
A.
shouldn’t have gone
B.
might have gone
C.
needn’t have gone
D.
must have gone
【单选题】he has told us, we will be punished for not having finished the work in time.
A.
Which
B.
That
C.
As
D.
What
【单选题】锰和镍（Ni）都是金属元素，将镍丝插入MnSO 4 溶液中无变化，插入CuSO 4 溶液中，镍丝上有红色固体析出．Mn、Ni、Cu三种金属的活动性由弱到强的顺序是（ ）
A.
Mn、Ni、Cu
B.
Ni、Cu、Mn
C.
Cu、Ni、Mn
D.
Mn、Cu、Ni
【判断题】Preventable adj. 可阻止的,可预防的 ; [ 例句 ]Forty-thousand children a day die from preventable diseases 每天有 4 万个孩子死于本可以预防的疾病。
A.
正确
B.
错误
【单选题】I regretted not having finished my composition last night, I ____ go the cinema with Mary.
A.
shouldn’t have gone
B.
might have gone
C.
needn’t have gone
D.
must have gone
【简答题】交易文件的完整性得以保证是因为应用了
【单选题】Section A Choose the best translat ions for the following sentences. 1. Not having finished his homework, John was punished by his mother.
A.
没有完成作业，约翰被他妈妈惩罚了。
B.
因为没写完作业，约翰得到了妈妈的惩罚。
C.
由于没有写完作业，约翰受到了妈妈的惩罚。
D.
没写完作业，约翰受到了妈妈的惩罚。
【单选题】Not having finished their jobs, _____ to leave the company.
A.
the boss forbade them
B.
they were forbidden
C.
so they were forbidden
D.
and they preferred
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