The terrible accident is under investigation.— Actually, quicker action ____ those workers trapped in the mine. [ ]

Now lots of teenagers spend a lot of time playing computer games.—Yes. Teachers and their parents should prevent them ____________ too much.

With the environment worsening, the government ______ people for more environment protection．

By the time Jack returned home fromEngland, his son _____from college.

Look at that tall building!—It is _______tallest building in the city.