Tomplacedthebanknotes,_________thechangeandreceipts,backinthedrawer.
Inmostcountries,themetricsystemhasbeen_____forallmeasurement.
关于x的方程x+ax+b=0有实根。
(1)a+b=0
(2)a-b=0
ExcelEnergyCorporation'snewonlinetrainingprogramhas_______(interact)featuresandforumdiscussionsfortrainees.