【单选题】He is __________ at music. So he plays the piano ___________. [ ]
【简答题】什么叫互感和互感电动势?怎样判定互感电动势的方向?
【单选题】He is a swimmer, and he swims very _____________ .
【简答题】The manager “a” fallen asleep where he ______, without undressing. A. was laying B. was lying C. had laid D. had lied
【简答题】什么叫自感现象、自感电动势和自感?什么叫互感现象、互感电动势和互感?
【判断题】环境温度和湿度以及试样放置时间等因素能引起塑料分子量、分子构型、物理态的变化,影响到应力的消存等,所以PA6试样长时间放置其冲击强度会变低。
【判断题】环境温度和湿度以及试样放置时间等因素能引起塑料分子量、分子构型、物理态(分子链的运动)的变化,影响到应力的消存等,所以PA6试样长时间放置其冲击强度会变低。
【简答题】互感线圈由于电流变化所产生 的自感电动势的极性与互感电动势的极性始终一致的端点叫 。