With question tags:

(1)He's posted the letter, ________ ?

(2)You hardly know each other, ________ ?

mood

ellipsis

the non-finite verbs

What's the difference between regular passive and the pseudo-passive?

discontinuity

Using subjunctive mood:

You're hungry now because you didn't have breakfast.

What is the difference between the infinitive marker to and the preposition to? Give one example for each.

Using a tag question:

You have already got our invitation.

Using extraposition:

To drive without a license is illegal.

Using an exclamation:

They are working very fast.