In January, 2004, the United States successfully launched “Spirit”, a Mars Exploration Rover, _____ a new milestone in the history of mankind.
—Why did you cancel your trip to the New York? —We were just about to leave_______ it started to snow.
Dr.Frank failed many times but he finally _______ to find a successful way to solve the problem.
—Are you pleased with what he has done? —Not a bit .It couldn’t be ________.
_____ scores of times , but he still couldn’t understand it .
We waited and waited._________ we had been looking forward to .