What has changed the Nuclear Family in North America

A．People have changed their ideas about marriage.

B．Women become more independent.

C．The economy is changing.

D．All of the above factors are acting together.

当诊断参数测量值处于（）范围内时，表明诊断对象技术状况良好，无需维修便可继续运行。

A.初始值

B.许用值

C.极限值