摘要：如图.要使L1和L2两灯并联.必须( ) A.闭合S1.S2.S3 B.闭合S1.S3 C.闭合S2.S3 D.闭合S1.S2

网址：http://m.1010jiajiao.com/timu3_id_1415298[举报]