.---There is a lot of smoke coming out of the teaching building.---Really? It _____be a fire, most probably.
According to a recent U.S. survey, children spent up to 25 hours a week _____ TV.
There is a new problem involved in the popularity of private cars _____ road conditions need _____.
An army spokesman stressed that all the soldiers had been ordered _____ clear warning before firing any shots.
The pale face of my friend suggested that he ______ in poor health, and I suggested that he ______ to see a doctor.
______ is obvious that reading in bed does great harm to your eyes.