Mary made coffee ________ her guests were finishing their meal.
The famous scientist, _______ a dinner party will be held tonight,is to arrive soon.
__________twice a year, whether it is a car or bus or a truck, is the rule that every driver must obey in this city.
--- An ant has two stomachs --- one for itself, one for others.--- Really? Quite interesting. I ____ anything about it.
AIDS is said__________the biggest health challenge to both men and women in that area over the past few years.
______ only 20 minutes to go before the train left, I felt uneasy in the taxi to the railway station.