John's success has nothing to do with good luck. It is years of hard work has made him what he is today.
To learn to swim well, ___________.
The next thing he saw was smoke ______ from behind the house.
They began to think about what use could be ______ such materials.
Tom ______ close the window when his attention was caught by a bird.
He has made some spelling mistakes in the paper; ______, they are not serious.