在责任保险实务中，（）是确定责任保险责任事故有效期间的方法。
A.承保方法
B.承保时间
C.承保环境
D.承保基础
参考答案：D
Some of the stamps belong to me, while the rest are .[ ]
A. him and her
B. his and she
C. his and hers
D. his and her
下列能作为对比剂的物质有()
A．碘油
B．碳酸钡
C．硫化钡
D．氯化钡
E．碘酒
