--Look! Someone ____ the floor.It's clean.--Well,it wasn't me I went shopping just now.
—What’s _____most useful invention in the 20th century? —_____ computer, I think.
— Tom, you are going to buy a new flat here, aren’t you? — Yes, but I can’t _____an expensive one.
—Open the window, please. —Certainly. Which one? _____ beside the door?
—I’m going to take my driving test tomorrow. —_____!
I felt it hard to keep up with my classmates. But when I want to _____, my teacher always encourages me to work harder.