---Who was calling you on the phone just now？

---_______.

That's him

It was Tom

This was someone

Maybe Jim's

考查强调句。句意---刚才谁在电话里面叫你？---他是汤姆。根据题意，答句为强调句。完整形式为it was Tom that call you on the phone just now.缩写形式为It was Tom，故选B。

---I'm sorry,but it's my seat.

---           I didn't know it's yours.

What if

I beg your pardon

That's all right

What for

考查交际用语。句意：---对不起，这是我的座位。---请原谅。我不知道这是你的。A. What if如果.....将会怎么样；B. I beg your pardon. 对不起，请原谅；C.That's all right没关系；D. What for为什么。根据"Idon't know it's yours."可知坐了别人的座位，请求别人原谅。故选B项。

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。