关于高频电疗的介电常数的说法错误的是（）。

A.又称介电常数，介质加入电场后对电场特性发生影响

B.表示某介质加入电场后对电场特性影响的程度

C.一般物质的介电常数约为1

D.皮肤的介电常数为10～20

E.同一组织在不同频率电场中的介电常数不同

VRML is a （71） for 3D multimedia and shared virtual worlds on the WWW. In comparison to HTML, VRML adds the next level of interaction, structured graphics, and extra（72） (z and time) to the presentation of documents. The applications of VRML are （73）, ranging from simple business graphics to entertaining WWW page graphics,manufacturing, scientific, entertainment, and educational applications, and 3D shared virtual worlds and communities.X3D is the name under which the development of VRML is continued. X3D is based on XML and is backwards （74） with VRML. Furthermore, it is componentized, profiled, and extensible, which makes it possible to use X3D in very different （75）, from high-end visualizations to lightweight applications.

A．link

B．format

C．structure

D．procedure