English for more than six years, he can speak and work very well with that businessman from England.
--Do you know anyone in Paris? --No, I’ll make friends once______ .
The research is so designed that once ______ nothing can be done to change it.
He is always______fault with other people though he doesn’t do his own work properly.
Meeting my uncle after all these years was an unforgettable moment, ____ I will always treasure.
Hardly ______ when the bus suddenly pulled away.