A hard-working man _____ become a great scientist, but a great scientist _____ be a hard-working man.
----Have you finished writing the letter_______? ----Not ______
He’s gone to the library ,_______ he ?
---Did you get there by _____bike? --- No, I took _____taxi.
—Why don’t you divide the students into six groups? —_________.
Mr. Green didn’t post the letter _________. He asked his son to do it for him.