Those boys _____ many times not to go on line, but it doesn’t make any difference.

—Why were you so late this morning?
—I _____ in heavy traffic for an hour on the way here.

We consider it necessary that a plan _______ before doing the work.

By the middle of the 21^st century, the vast majority of the world’s population _____ in cities rather than in the country.

--- You look very tired. _____ at all last night?
--- No, not really. I’m tired out now.

---Allen, are you coming with us?
---I’d love to, but something unexpected ____.

My boss______for Beijing in a few days. Do you know when his plane______?

As a teacher, he is ______ to work hard and must be strict in his work.

- What's up? You didn't pick up the phone just now.
- I'm sorry that I     dancing with music on, but it's done now.

--Remember the first time we met?
---Sure. You _____________ the novel Gone With the Wind in the library.