一、用所给动词的适当形式填空
1.A teacher of English and class teacher ________ (tell) us something about volunteer workers now.
答案与解析 is telling 句子主语为“英语老师兼班主任”为一个人，故后面的谓语动词要用第三人称单数形式，从now可知，用现在进行时。
2.When and where this took place ________ (be) still unknown.
答案与解析 is 主语为主语从句，虽由and连接但却指的是同一件事，故谓语动词用单数形式，且表示被动，故填is。
3. Every means ________ (try), but none proved successful.
答案与解析 has been tried means的单复数同形，从every可知这里是单数，因此谓语动词也用单数，而且根据句意可知，是“每个办法都被尝试过了”，故用被动语态。
4.Weibo as well as WeChat ________ (serve) as a media platform for people to share their thoughts instantly without limits of place or time.
答案与解析 serves 句意：微博和微信可以作为一个供人们随时随地分享他们想法的媒体平台。serve as表示“可用作，可当……使”。由as well as可知，该句的谓语应由Weibo而定，故应用第三人称单数形式serves。
