One of the man holds the view          the book said was right.

that

whether

what that 

that what

考查同位语从句及主语从句。句意：其中一个人认为这本书说的是对的。分析句子可知，the view后面接了一个同位语从句（     the book said was right.），从句句子成分齐全，应使用that 引导，连接词在从句中不做成分，无意义。在同位语从句中又有一个主语从句（     the book said），在主语从句中said 缺少宾语，应用what 引导，指代“......的（事情，东西）”。故选D项。

Only when he returned ________ that the war had ended and the army had come back.

we tell

we told

did we tell

were we told

考查倒装句型。Only放在句首时，句子要用倒装语序；根据句意“我们被告知”可知，此处要用were we told。故答案选D。

A study shows the students who are engaged in after-school  activities are happier than        who are not.

ones

those

these

them

考查代词。句意：一项研究表明，参加课外活动的学生比不参加课外活动的学生更开心。空格处代词与the students是对应关系，可以用the ones 或者those替代。“them”指代前面提到的复数名词，不能与the students形成对应关系，“these”一般不用定语从句修饰。故选B项。