We spend about one-third of our lives sleeping. We know relatively little about sleep.

I am sure he did not know that his brother graduated with flying colors.

If he wrote to her, she would be happy.

Start at once or you will be late.

The garage serviced my car last week.

Overeating is a cause of several deadly diseases. Physical inactivity is another cause of several deadly diseases.

They couldn’t think of anything better to do. They decided to baby-sit for the family.

He didn’t take his father’s advice. That’s why he is out of work.

Most people get fewer colds in the summer than in the winter.

The car was very expensive and he couldn’t afford it.

The train should be here any minute now.

Would you mind waiting outside the office?

Without your help, I couldn’t have succeeded.

James did not come. He did not call either.

The train drivers' strike made it hard for us to get to work.

“You have just got a promotion, haven’t you? Congratulations!” Peter said to his friend.