The 2012 Summer Olympic Games ______, taking place in London for a third time this summer.
Mary _______ her mother with the housework, but she didn’t.
The local government announced that only when the fire was under control ________ to return to their homes.
He left home without saying a word, and _______ worries many people and is to be found out.
He came all the way to China for learning it better _______ for making money.
Evidence gained from observation and experiment is often used to _______ a scientific theory.