—I have worked hard at math, but it seems that I haven’t made any progress. —Keep on _____ at it, and you will be successful. A. work B. working C. to work
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.
—Where is your English teacher?I’m looking for him everywhere.—He________for some information on the Internet in the computer room.
They________in the city since last summer.