Lawrence Craven, a doctor from the USA, is the author of several published reports, one of which introduced the idea in 1953 ________ aspirin could reduce the risk of heart attacks by thinning blood.
I took them _____ because I didn't know which was the best.
—Are you going to watch the game? —I'm sure _____ ,for it promises to be a close one.
—The problem isn't difficult for the children to work out, is it? —_____ . Perhaps they should have been given a more difficult one.
—Shall I tell John about it? —No, you _____ ,I've told him already.
_____ is known to all, paper was first made in China.