Shelly had prepared carefully for her biology examination so that she could be sure of passing it at her first .
The pianist waited for silence a while _______ he began to play the violin.
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.