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。

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。