He is a man of few words, and seldom speaks until _______ to.
twice a year, whether it is a car or a bus or a truck, is the rule that every driver must obey in this city.
---Are you a teacher? ---No, but I _______.
Before he went abroad,he spent as much time as he _____ English.
As time went by, the plan he stuck ____ fairly practical.
The detective,____ to be reading a newspaper, glanced at the man_____ next to a woman.