.When he was only thirty years old, he had already experienced ___________ most people only experience when they are much older.
He was told that it would be at least three months ___ he could recover and return to work.
Scientists are convinced ___ the positive effect of laughter ___ physical and mental health.
We had to wait half an hour _______ we already booked a table.
Help others whenever you can ______ you will make the world a nicer place to live in.
Most birds find it safe to sleep in the trees, but ____ they have eggs or young chicks, they don’t use a nest.