Ecologists are trying to preserve our environment for future generations by protecting the ozone layer, purifying the air, and have planted the trees that have been cut down.

Jason’s professor had him to rewrite his thesis many times before allowing him to hand it in.

When a patient’s blood pressure is much higher than it should be, a doctor usually insists that he will not smoke

Robots in the home might not be enough creative to do the cooking, plan the meal and so on.

Spell correctly is easy with the aid of a number of word processing programs for personal computers. 

Unless there had been a heavy storm, the climbers will not have died.

The chief of police demanded from his assistants an orderly investigation, a well-written report, and that they work hard.

The deadbolt is the best lock for entry doors because it is not only inexpensive but installation is easy.

What happened in New York were a reaction from city workers, including firemen and policemen who had been laid off from their jobs.

Before went abroad, he had finished his English course at the English-speaking Center.

Today's job seekers are confronted with such question as "Are you computer literate?" and "Can you set up a data base?" 

This apprentice has spent two weeks to work on that new machine.

Do most boys and girls give a great deal of  thought to their future employ ?

It has ever been told that teaching is one of the more noble careers.

Teddy Roosevelt demonstrated  his competitive spirit and tireless energy in 1905 whenever he led the Rough Riders up San Juan Hill

Conservation is the safeguarding and preservation of nature resources.