利用DTD定义元素的属性时，如果该属性有默认值，但没有给出缺省值说明，则在XML文档中不允许对该属性的值进行更改。

Speker: Do you mind if I open the window Speker B: ______Yes, plese open the windoSpeker: Do you mind if I open the window Speker B: ______Yes, plese open the window. B．Yes, I do find it is very stuffy in the room. C．No, I don’t. Don’t open the window plese. D．s mtter of fct, I’m feeling bit chilly.A．Yes, please open the window．B．Yes, I do find it is very stuffy in the room．C．No, I don’t． Don’t open the window pleaseD．As a matter of fact, I’m feeling a bit chilly．

—Do you mind if I open the window — ____________.Yes, pleseB．No, but I doC．No, gohedD．No, you—Do you mind if I open the window — ____________.Yes, plese B．No, but I do C．No, gohed D．No, you’d better notA．Yes, pleaseB．No, but I doC．No, go aheaD．No, you’d better not