This is not ()of the United States or Europe.
The right words for the blanks areindeed, believing, fence, enough.A friend in need is a friend ___________.Seeing is _________.Mend the ___________ when the weather’s better.Enough is _________.()
In some countries, New Year‘s Eve is the most important celebration of the year, but this
电压源 电动势为 3V ,内电阻为 0.3Ω ,当外电路断 路 时,电路中的电流和电源端电压分别为 ;当外电路短路时,电路中的电流和电源端电压分为