I'm going to have to (do something)

Use this phrase to talk about something that you need to do, but which might annoy your listener.

I'm going to have to charge you extra for that. Sorry!

A: We're going out for a bite to eat. Why don't you join us?

B: No, I'm going to have to take a rain check. 

This is similar to "going to need to". "Going to have to" is friendlier-sounding, though.

There's also another way to use "going to have to", which is just to talk about things that you have to do in the future. Here's an example:

Just a heads up - we're going to have to meet soon.

re(do something)

The prefix "re-" means "again". You can attach it to a lot of different words. For example:

• resend
• retype
• redraw
• rewrite
• rethink

In all of these examples, adding "re" means to do the action again.

scan (something)

Checking something with a machine is "scanning" it. Here are some examples of "scanning":

• At a store, the cashier may scan the label of an item to find out how much it costs.
• An X-ray machine scans your body or the inside of a piece of luggage.
• The military uses technologies like radar to scan the air and water.

Sir, (sentence)

Employees who deal with the public, like cashiers, receptionists, security guards, hotel staff, etc. often call male customers "Sir". It's supposed to show respect. For example:

Sir, can I get you something to drink while you wait?

In the U.S., you can also call any adult man who you don't know "Sir".

On the other hand, it's a little strange to call someone "sir" who you know well, like a coworker or friend. Unless someone has a clear position of authority over you (like a teacher), don't call him "sir" if you've had friendly conversations with each other.

The equivalent title for women is "Ma'am".