题型:判断题 . She _____ on this essay for twenty minutes but she has written only about a hundred words.A.will be workingB.workedC.has been workingD.will have worked 查看答案
题型:判断题 如图所示,是某科技实验小组的同学通过实验探究发电机与电动机原理时,设计的装置图,闭合开关S,先将导体ab水平向右移动,导体cd也随之运动起来,可知:(1)实验装置左侧ab导体运动时电路中产生的现象是____________,根据此现象的原理制成________机。ab导体水平向右移动时将__________能转化为__________能。(2)实验装置右侧cd导体产生的现象是利用___________导体在磁场中___________而运动的,此原理可制成___________机。 查看答案