日本核事故释放出的极微量人工放射性核素131I,它能引发甲状腺癌;但127I却是人体必需的。127I可阻隔甲状腺吸收放射性131I。碘盐含127I为 30 mg·kg-1,成人一次摄入碘盐约3 kg才有预防效果。 下列有关说法不正确的是( )A.131I与127I互为同位素 B.相同物质的量的131I与127I的质子数不同C.131I与127I 是两种不同核素 D.日用碘盐对预防碘辐射起不到有效作用
从所给的四个选项中选择最佳答案
—She isn't a student, is she?
—________.She is a teacher.
[ ]
A.Yes, she isn't
B.No, she is
C.Yes, she is
D.No, she isn't