What’s that smell? —- I don’t know, but ______ it is, it’s terrible!

I’ve finally finished my paper and it _____me an entire month.

You won’t discover the truth ______ you look into the matter yourself

It was with the help of the local guide ________ the mountain climber was rescued.

What are you doing here, Mrs. White—I’m waiting for my son. He________ back from school.