逐步激发

step-by-step

step-by-step call indicator

stagewise regression【数】;step-by-step regression【数】;stepwise regression【数】

step-by-step relay【通信】 电;stepping relay【通信】 电

step-by-step procedure

step-by-step, actuation

step-by-step automatic telephone system【通信】

step-by-step switch testing equipment