Olympic Games, only athletes whohave reached the agreed standard for their event will be ______ as competitors．

You can only be sure of_________ you have at present; you cannot be sure of something _____ you might get in the future

Andrea Bacilli never_____, which makes him a successful singer.

So mysteriously ______ missing that many puzzles wait to be solved.

Do you know how I can ________ him? — On his mobile phone．