payment is due (when)

When you're making a rule or re-stating a rule about when someone is supposed to pay a bill, use this phrase. As an example:

My car payment is due by the 15th.

You can also use other words that mean something similar to "payment" in a similar way:

When is the mortgage due?

Her rent was due last week.

This is a phrase that is often used in written documents, and in conversation as well.

receive (something)

To "receive" something basically means to get it from someone.

We received over a hundred submissions.

The word "receive" is pretty formal. It's used in official documents or in business communication. In normal conversation, "get" is more common:

We got over a hundred submissions.

"Receive" is often used in a pair with the word "give" - there's a famous saying "It's better to give than to receive."

be (done)

Sentences with "will be" like these:

It will be fixed

...mean that someone will do something. You avoid saying exactly who will do it by using this structure. 

You might speak this way if you don't know who did an action:

It's been fixed.

Or if you want to hide who did it:

I was told not to say anything.

Another reason to use "be done" is for politeness. Instead of directly telling someone what to do:

You have to fasten your seatbelt.

...you can instruct people more politely like this:

Seatbelts must be securely fastened.

(do something) within (a length of time)

You can use the word "within" to talk about time:

The letter said that I needed to respond within 3 days.

"Within" a length of time means before the end of that period. So "within ten seconds" would mean before the end of the tenth second.

People use "within" to talk about deadlines or time limits.

charge (someone) a fine

A "fine" is money that you have to pay because you did something wrong. For example, banks make you "pay a fine" if you try to take out more money than you actually have in your account.

When an organization makes someone pay a fine, we use the word "charge":

If you don't return them on time, the library will charge a fine.

You can say how much the fine is like this:

I was charged a $50 fine for filing after the deadline.