–What do you think of teaching, Bob?–I find it fun and challenging. It is a job ___ you are doing something serious but interesting.
Scientists say it may be five or six years _______ it is possible to test this medicine on human patients.
It was some time _______ we realized the truth.
Roses need special care _______ they can live through winter.
This photo of mine was taken _______ stood the famous Eastern Bright Pearl in Shanghai.
You should made it a rule to leave things _______ you can find them again.