6. Guess the meaning of the following idioms, then fill in the gaps in the sentences below.
As thick as thieves – crime doesn’t pay – daylight robbery – set a thief to catch a thief
1. The police tracked down the killer with the help of a convicted murder – as the saying goes, …………. .
2. “They charged me 40 pounds for that terrible meal! That’s ……………..!”
3. Keith and Jack are ……………. ; they spend all their free time together
4. “You shouldn’t even think of stealing money from the company; you should know that ……………………”