.They ___ out because the light’s on. Let’s go upstairs and have a look.
I got to the lecture hall very early, ______ to get a good rest.
It hasn’t been announced ______ the plane is to take off.
Students ______ to do some voluntary work every year.
You can smoke here ______ you leave a window open to let the smoke out.
It is usually cheaper to have the goods ______ by sea than by air.