Mr. Black, as far as I know, is said _______ a book on the history of the Ming Dynasty, which turns out to be a bestseller.
—What led to his success ? —He succeed _____ working hard .
.I don’t think that the sentence need ______again.
—Of the two apples , which one do you prefer ? —________ bigger one . It’s_____most delicious one , I think .
Though ___ to stop to take a rest, the workers went on working till sunset.
The girl student came into the classroom, took a chair, sat down and____ to read,____very comfortable and happy.