--- Must I return the book today? I haven’t finished it.---It depends on how long you have ____________ it? You should return it two weeks.
Frank ______ to see his grandpa if he ______ free tomorrow.
— ______ salt do we need? — One spoon is enough.
I’m going to ______ a new hobby. I want to learn how to take photos.
Robots are ______ do the same things as we do.
Tigers wait ______ it is dark, then they go out to find their food.