Brain, like muscles, also needs some kind of exercise and nutrition. The more you use your brain in the right direction, the more you ________ enhance your ability.

We all know that we ________ our carbon footprint, but I suspect that many people wouldn't be prepared to go as far as Joan Pick, a retired scientist living in south London.

—You will never believe that it took us two hours to get to the restaurant.
—Really? You ________ in a traffic jam.

—Jim is very sick these days. He coughs so badly.
—In my opinion, he really ________ listen to the doctor and cut down on smoking.

—Where did you get this book?
—I picked it up from a second­hand bookshop if you ________ know.

When Harry was at college, he ________ go to the reading room after supper every day.

Your teacher ________ very angry at that moment because you talked back to her like that.

Oh, I'm not feeling well in the stomach. I ________ so much fried chicken just now.

—The research on the new flu virus vaccine is challenging and demanding. Who do you think can do the job?
—________ my students have a try?

Martin hasn't got in touch with me for ages. He ________ my new cell phone number.