As more and more cars are produced and used, so the _____ from their exhaust-pipes contains an even larger volume of poisonous gas.

I broke my relationship with John because he always found_______ with whatever I did．

  The professor combines different ________ in the same speech.

The students were advised to try a different ________ to solving the complex maths problem.

David is the current holder of the 5,000-meter world record, but there is no ____ that he will win in the Olympic Games.