Do you think Mom and Dad ________ late—No. Swiss Air is usually on time.

He was born in a Chinese immigrant family who made their living_____ duck farming and fruit trading.

I remembered ________ the door before I left the office, but forgot to turn off the lights.[ ]

The mixture of his improved self-confidence and never-ending efforts is ________ lies behind his rapid progress in his study.

I’d love to make friends with the boy ____ you think is easy to _____.—OK. I’ll introduce you to him at the party.