短语，谓语动词的单复数与主语一致，且主语与谓语之间为被动关系。

　　Ⅲ.单句改错

　　1．The United States are made up of many states.(are→is)

　　2．Politics are related to facts closely.(are→is)

　　3．Many a student have a mobile phone.(have→has)

　　4．To have a sunbath are helpful to our health.(are→is)

　　5．Playing basketball are good to lose weight.(are→is)

　　6．What I want now is some reference books.(is→are)

　　7．When and where they will go climbing are unknown.(are→is)

　　8．The composer and musician are world－famous.(are→is)

　　Ⅳ.完成句子

　　1．__What we badly need are__ good teachers.

　　我们急需的是好老师。

　　2．To prevent the air from being polluted __is what we're now researching__.

　　防止空气污染是我们正在研究的课题。

　　3．Whether they will hold a party or not __has not been decided__.

　　他们还没有决定是否开派对。

　　4．Steve，together with his wife and children，__is arriving tonight__.

　　史蒂夫跟妻子和孩子们将于今晚到达。

　　5．All __are eager to__ reach an agreement.

　　大家都急于达成一项协议。

　　6．None of the telephones __is/are working__.

　　电话中没有一部不是坏的。

　　7．Each of the books __costs five yuan__.

　　每本书5块钱。

　　8．Quantities of time __were spent__ in saving the wounded.

　　大量的时间被花在救护伤员上。

　　9．A number of houses __were built__ there three years ago.

那儿很多房子建于三年前。