-- Can I call you back at two o'clock this afternoon?-- I'm sorry, but by then I ____ to Beijing. How about five?
Both rice and wheat _____ grown in our country.
Mathematics _______ the language of science.
Stories of the Long March _______ popular with the young people now.
Three million tons of coal ______ every year in the city.
There _____ a lot of rubbish on the floor so I asked Mary to sweep _____ up.