Previously ______ at a fast food restaurant, the Smiths were dissatisfied with the unhealthy meals they served there.
He is ____our teacher; he is also our best friend.
--Why does the river smell terrible?--Because large quantities of water__________.
_______that they lost the game, tears came down Kate’s face.
Children’s brains can’t develop properly_______ they lack protein(蛋白质).
With all his attention ____ on the computer game, the boy even didn't notice his mother came in.