Police sealed off the town – centre for two hours meanwhile they searched for the bomb.

Electric motors range in size from the tiny mechanisms that operate sewing machine to the great engines in heavy locomotives.

Every scientist knows that gravity is the force that maintains the earth and the planets in its orbits around the Sun

The most of the energy used in our homes and factories is generated from coal, oil and natural gas

A number of the Pacific Islands are volcanoes that have pushed up from the ocean floor, the others are the tops sunken mountain ranges

Jack London, whom was known for his stories of Alaska, lived there during the Klondike gold rush.

The office …………on the weekend.

One of the most difficult questions in defining sleep is “What are the functions of sleep?”

Choose the correct answer to complete the sentence. "In the past, a lot of countries ______ having contributed to global warming"

To those who favorite free trade, the revival of barter can suggest nothing less than a disaster.

Many birds will, in the normal course of their migrations, flying more than three thousand miles to reach their winter homes.

It is possible for local wildlife to coexist ...... industry.

In a person’s lifetime, the brain can store 100 trillion pieces of informations.

When my lost briefcase was returned with my year-long research results intact, I felt tremendously relieved. It was as if a huge heavy weight ______________ from my shoulders. 

That lecturer, his name I have forgotten, is very well-known

Ocean currents that help transfer heat from the equator to the poles, thereby creating a more balanced global environment.

Choose the correct answer to complete the sentence. "One of the main greenhouse gases that lead to global warming _____ carbon dioxide"

Jack had to skip breakfast otherwise, he will be late for class.

Choose the best option:

The problems of pollution call for a prompt ___ from the government.

 I told Mom we would be ...................home in ...................hour or so. 

After driving for twenty miles, he suddenly realized that he has been driving in the wrong direction.