常用的直流斩波电路有降压斩波器、升压斩波器、( )等。
A、数字斩波器Theengineer______myfatherworksisabout50yearsold.
Helost________________parentswhenhewasachild.
Theattitudetowardslifethat()hadbeentryingtodemonstrateinhisworksisknownas“graceunderpressure”.
Heinsuredhiscar________hehadanaccident.
Theirplanearrived________SanFranciscothismorning.
