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。

They elected him          captain of the team for         second time.

the; a

a; the

a; a

/; a

考查冠词的用法。句意：他们再次选他当队长。职位，官衔前面不加冠词，a second time表示“又一次，再次”；the second time表示第二次（顺序）。故选D项。

It is said that railway station is now         large as What it was.

as twice

twice as

twice much

much twice

考查倍数表达法。句意：据说火车站现在是原来的两倍大。倍数的基本结构一般为“A+倍数+as+形容词或副词的原级+as+B”，表示“A正好是B的多少倍”。联系下文large as，此处用twice as large as 表示“是.....的两倍大”。故选B项。