问题
单项选择题
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．Web
B．E-mail
C．DNS
D．FTP
答案
参考答案：A
，则f（x）在（0，π）内的正级数的和函数s（x）在处的值及系数了b3分别为（）。
