Finding information in today's world is easy.The ________ is how you can tell if the information you get is useful or not.
One day, _____,Newton saw an apple fall from a tree.
He made another wonderful discovery, _____ of great importance to science.
As I know,there is _____ car in this neighborhood.
_____,success results from hard work.
_____ the general state of his health,it may take him a while to recover from the operation.