The professor could hardly find sufficient grounds________ his arguments in favor of the new theory.
As the busiest woman in Norton,she made_________her duty to look after all the other people’s affairs in that town.
The chairman thought________necessary to invite Professor Smith to speak at the meeting .
—How was the 2008 Beijing Olympic opening ceremony? —________ that the whole world was attracted.
________should the young _______illegal behavior.
_______,but it is also a great way to lower the number of greenhouse gases in the air.