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参考解析：
刷刷题刷刷变学霸
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
【多选题】在PN结实验中,如何控制加热电流,保持温度的平稳上升( )
A.
开始时选择一个较大的加热电流
B.
开始时选择一个较小的加热电流
C.
整个实验中升温速度要慢
D.
最高温度最好控制在120℃