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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】吸氧过程中需要调节氧流量时，正确的做法是
A.
先关总开关，再调氧流量
B.
先关流量表，再调氧流量
C.
先拔出吸氧管，再调氧流量
D.
先拔出氧气连接管，再调氧流量
E.
先分离吸氧管与氧气连接管，再调氧流量