27, fill in for 代替; 同义：fill one’s place(position, shoes); take the place of; take over Say, Dave, can you fill in for me tonight at the restaurant? I’d like to go out of town.
28,food for thought 令人思考的东西;同义：thought-provoking
There is a lot food for thought in what he had to say.
29,for nothing 免费
To pay to see that movie would be foolish, when you can see it on TV for nothing.
30,from top to bottom 从上到下
A: Maybe you lost your wallet in this room.
B: I’ve searched it from top to bottom..
