________its low cost, the appeal of iron as a building material lies in its strength, its resistance to fire, and its potential to span long distances.
As is well known, carelessness and irresponsibility _______ many deadly accidents.
They ___________ for two hours
Taiyuan,a city in North China,was struck by a heavy snowfall last week,________serious traffic problems.
It was not until the beginning of the twentieth century________to explore space.
A notice was________in order to remind the students of the changed lecture time.