The (72) is a system for linking hypertext documents Originally, each document was a page written in (73) with hyperlinks to other documents．Nowadays，XML is gradually starting to take over from (73) ．

A．JSP
B．HTML
C．ASP
D．PHP

目前普遍应用的振动式电喇叭，是利用（）的变化吸动振动盘发生声频振动来发出声波的。

A.电压

B.电阻

C.电流

D.电动势