第19题: [单项选择]A person can visit a ( ) at any time or at any point in the discussion and enter the conversation by responding to a question or posting his or her own article. A. FTP B. E-mail C. WWW D. newsgroup 参考答案:D
第20题:[多选题]屈光不正包括( ) A. 老视 B. 近视 C. 远视 D. 散光 E. 屈光参差 参考答案:BCDE