think it over

To "think it over" means to think about something that you have to make a decision on. In the example above, the job applicant has to "think over" whether to take the job.

This expression almost always uses "it":

Let me think it over.

If you don't use "it", the word order changes:

Have you thought over my offer?

A more formal word that means something similar to "think it over" is "consider". You would write this if you were offering someone a job in writing:

Please consider our offer and let us know what your decision is by next Thursday, March 10th.

let (someone) know

"Let me know" means "tell me". But "let me know" is a more polite and friendly expression. It's very common to hear in an English-speaking workplace:

If anything comes up between now and then, just let me know.

You can also use it with friends:

Let me know when you're finished with the computer.

(a period of time) or so

This is an expression for talking about time loosely. "The next week or so" means "about the next week". It could be in 5 days, in 10 days, etc.

I'll be travelling for the next week or so.

Other phrases that use "or so" include:

• the first day or so
• the last year or so
• for an hour or so

For example:

This is one of the best songs I think I've heard in the last decade or so.