At times, worrying is a normal, ________ response to a difficult event or situation --- a loved one being injured in an accident, for example.
It’s just _____among countries to host the Olympics as to win an Olympic Medal.
Do ____ you think is right, ____ difficulties you may have.
---Why can't I smoke here? ---At no time__________ in the meeting-room
______ it is true that a student’s most important goal is to do well in his or her studies, it doesn’t need to be the only goal.
He devoted most of his time to his research, believing his hard work would___sooner or later.