如图所示的电路中,电源电动势为6V,当开关S接通后,灯泡L1和L2都不亮,用电压表测得各部分电压是Uab=6V,Uad=0,Ucd=6V,由此可判定( )
John as well as the other children who ______ no parents ______ good care of in the center.
已知等腰梯形的上底是10厘米,下底是25厘米,腰是15厘米,那么它的周长是( )厘米.