—How long does it take to get to the airport?—Forty minutes.But it’s foggy today.I’m not sure________the highway will be closed soon.Let’s set off earlier.
—________she________doing her homework yet? —Yes,she has.She________it just now.
She has been in the city________.
Why don’t we consider________the Great Wall next weekend?
That clever boy regards the problems________challenges.
There are________people leaving the countryside to search________work in the city.