It's high time that we students ______ even harder at our lessons as the national entrance examination is coming nearer.
The buses, ____were already full, were surrounded by an angry crowd.
If we work with a strong will, we can overcome any difficulty, _____great it is.
--- My son is _____ to be seen. Where has he gone? --- I think he _____ in the building.
His grandfather was among the first to settle in _____ is now a famous holiday center.
No sooner _____ to sleep than the telephone rang once more.