[grammar 2] Auxiliary verb 1

I may be sick.
I might be sick.
You must not enter the area.
You don't need to enter the area.
Need not enter.
Will you turn on the light?
Would you help me?

You had better go to the office at once.
You had better not play with him.
You had best leave right now.
You had best not sit up late at night
You ought to study today.
You ought not to do such a thing.
I used to play football when I was a child
I would go fishing when I was a child.
There used to be a hospital here.