If or Unless

We cannot go sailing ______ the rain stops.

• if

• unless

I won't talk to her ______ she apologizes to me.

• if

• unless

You won't be able to find the house ______ you get help from your GPS.

• if

• unless

I won't go ______ he is going.

• if

• unless

______ we don’t take the necessary measures now, we may have serious problems later.

• If

• Unless

______ you don't take notes you will have hard time studying later.

• If

• Unless

She must have graduated already ______ she failed a class.

• if

• unless

Jason is always cheerful ______ something really bad happens.

• if

• unless

I will never forgive you ______ you tell him the truth.

• if

• unless

You are not allowed into the casino ______ you are under 21 years old.

• if

• unless