题目

 New ideas sometimes have to wait a long time            .     A. before fully accepted           B. before being fully accepted     C. till are fully accepted         D. until being fully accepted 答案：B由图可知，A、B、C三种物质的密度ρA、ρB、ρC之间的大小关系是（ ）A．ρA＞ρB＞ρCB．ρA＜ρB＞ρCC．ρA＜ρB＜ρCD．ρA＞ρB＜ρC