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举一反三
【单选题】Most shoppers know the feeling. You stand in front of piles of organic produce and wonder what those premium prices are buying you over and above what you get from standard foods. Not a lot nutrition-...
A.
do not use naturally produced fertilisers
B.
produce carbon dioxide when removing weeds
C.
use high doses of weed-killer
D.
use too many resources to qualify for organic status
【单选题】Most shoppers know the feeling. You stand in front of piles of organic produce and wonder what those premium prices are buying you over and above what you get from standard foods. Not a lot nutrition-...
A.
they are approved by many experts
B.
C. they won’t cause diseases
C.
B. they taste better than standard foods
D.
they are free from pesticides
【单选题】曝气池的需氧量计算公式 O2=Q(Sa-Se)/f-1.42XvV/θC中，式中( )
A.
f---BOD5 和 BODu 的转化系数，约为 0.80
B.
1.42---细菌细胞的氧当量
C.
V---活性污泥系统的总体积
D.
Q---处理的最大日最大时污水量