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

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

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

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

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

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

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

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.