You must have waited here for a long time ,___________you?
Scientists say it will be five or six years _____ it is possible to test this medicine on human patients.
You very fast if you went from New York to Boston in six hours.
They want to make _______ clear to the public that they are doing an important and necessary job.
_____ the child to bed, she began to correct the pupil’s exercise.
____ with a difficult situation, Arnold decided to ask his boss for advice.