摘要：a.b.c.d是四条线段,下列各组中这四条线段成比例的是 ( ) A.a=2cm, b=5cm, c=5cm, d=10cm B.a=5cm, b=3cm, c=5cm, d=3cm C.a=30cm, b=2cm, c=0.8cm, d=2cm D.a=5cm, b=0.02cm, c=7cm, d=0.3cm

网址：http://m.1010jiajiao.com/timu3_id_777981[举报]