500kV变电站站用电源接法最不合理的是（）。

A.由主变压器第三绕组引接；

B.有较低电压母线时，从这类母线上引接两个站用电源；

C.无较低电压母线时，直接从高压母线上引一台站用变压器；

D.由附近的发电厂或变电站低压母线引接

Originally introduced by Netscape Communications， (71) are a general mechanism which HrrP Server side applications，such as CGI (72) ，can use to both store and retrieve information on me HTTP (73) side ofthe connection．Basically，Cookies Can be used to compensate for the (74) nature of HTTP．The addition of asimple，persistent,client-side state significantly extends the capabilities ofWWW—based (75) ．

A．fixed
B．flexible
C．stable
D．stateless