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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】如图为一种服务型机器人,其额定功率为 48 W ,额定工作电压为 24 V 。机器人的锂电池容量为 20 A ·h 。则机器人 ( )
A.
额定工作电流为 20 A
B.
充满电后最长工作时间为 2 h
C.
电池充满电后总电量为 7.2 × 10 4 C
D.
以额定电流工作时每秒消耗能量为 20 J