铅化合物的毒性大小主要取决于：（）
A.溶解度
B.化学结构
C.分散度
D.分散度及在人体组织内的溶解度
E.比重
参考答案：D
卫生间的地漏水封的最小深度，应是下列何项？（）
A．40mm
B．50mm
C．60mm
D．80mm
Which of the following groups is defined as "newlyweds"
Which of the following best describes the possible attitude of the reporter
A．Sympathetic.B．IndifferentC．Critical.D．Matter-of-fact.
