.Fifty years ago, wealthy people liked hunting wild animals for fun ________ sightseeing.
It was in the lab _______was taken charge of by Professor Harris ________they did the experiment.
________is it ________has made Peter ________he is today?
All workers in this factory are required to _______at the age of 60.
(2012年天津卷,2)The letters for the boss _______on his desk but he didn't read them until three days later.
In China,as we all know,brides are often dressed in red as it is a ______of good fortune.