The old rules have to be          because they only applied to the circumstances that existed when they were made a hundred years ago.

developed

established

observed

revised

考查动词的辨析。句意：老的规则需要被修改因为它们只适合一百年制定时的状况。A.develop发展；培养；B.establish建立；C.observe观察；D.revise修改，由because they only applied to 可知它只适用于以前，需要修改。故选D项。

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。

---I think you are different now.

---Of course，times have changed and________.

so have I

so I have

neither have I

neither I have

肯定的陈述句后，跟so+主语+谓语，表示强调：确实…，其主语与前陈述句的主语相同；肯定的陈述句后，跟so+谓语+主语，表示…也…，其主语与前陈述句的主语不同．根据times have changed，可知对另一个"我"说时代也已经变了，用倒装句，本句是现在完成时，含有助动词have，主语为I，在这里还用助动词have完成，故选A．

If you want to catch the first bus you'd better         for the bus station immediately.

set up

set about

set down

set off

考查动词短语辨析。句意：如果你想赶上第一班公交车，你最好马上动身去车站。A. set up建立；B. set about开始做.....;C. set down 记下；D. set off 出发，动身。结合上文If you want to catch the first bus you'd better可知此处指“动身，出发”，应用set off。故选D项。

          no bus,we had to walk home.

There was

There being

Because there being

It being

考查独立主格结构。句意：没有车，我不得不走路回家。根据句意，表示“存在”，要用there be 句型；分析句子可知，设空处应用非谓语动词，there be只有主动形式，故用现在分词；因为非谓语动词有自己独立的的主语no bus,所以此处是独立主格结构。故选B项。