[RonBee]

Let's start with let's. Except for some set phrases (example: "Let us pray") let us is almost always expressed as a contraction: let's.

Example:

• Let's go!

It is almost always used to express an imperative, thus:

• Let's do it!

However, sometimes it is used to express something like an admonition, thus:

• Let's do what we ought to do.

Sometimes it is used to make suggestion, thus:

• Let's keep this just between us.