John is very lazy. He falls ______ behind among the students.

 As a scientist, Madam Curie devoted herself ________ to her research and that was why she was given two Nobel Prizes.

You can’t go out because it is a stormy night;       , your homework hasn’t been done.

He is _____ tearing up what he has written and beginning over again.

 Jogging is an effective way to keep fit. _____ , swimming is helpful for bodybuilding.