The poor boy couldn't work the problem out. He wasn't ____ clever.
I won’t tell the student the answer to the math problem until he ______ on it for more than an hour.
Ladies and gentlemen, please fasten your seat belts. The plane _______.
I _______ in London for many years, but I’ve never regretted my final decision to move back to China.
I was giving a talk to a large group of people, the same talk I _______ to half a dozen other groups.
“You’ve left the light on.” “Oh, so I have. _____ and turn it off.”