Time seems to pass at the same rate ---- everyone, but Einstein’s theory of relativity shows that time is not constant ---- the Universe.

By creating a bird flu virus that could spread ---- mammals, biologists have sparked an urgent debate ---- how best to protect the public from biothreats.

Nicaragua’s economy is mainly based on agriculture, with fishing ---- the coasts, but it also has large deposits of minerals that are mined ---- export.

. ---- many countries in which adoption is practiced, there are variations ---- the age when children are adopted, and the type of adoption.

Biology classifies living things ---- groups on the basis of specific shared characteristics, and then these groups are arranged ---- a hierarchical system.

---- selective breeding, people have long exercised indirect influence ---- the genetic makeup of plants and animals; however, today genetic technologies make it possible to directly manipulate an organism’s genes.

Artists use perspective ---- to make the object appear to have dimensions ---- to cause it to appear close up or in the distance or to suggest a feeling of space.

. On 14 February 1990, the space probe Voyager I reached a distance of some six billion kilometres ---- the Earth, speeding away from us ---- its journey past the planets and into outer space.

Roger Revelle’s calculations about what happens to the carbon dioxide released ---- the burning of fossil fuels were correct ---- showing that much of it would end up in the sea..

As it had in World War I, Argentina proclaimed neutrality ---- the outbreak of World War II, but in the closing phase it declared war ---- the Axis powers..

Because of Earth’s rotation, a person near the equator travels a longer distance ---- a given time than does a person ---- higher latitudes..

---- the end of the 20th century, information economics became an increasingly important field of specialization ---- economists..

One of the great advances ---- astronomy ---- the past decade has been the discovery of planets outside our solar system. .

Monopolies are characterized ---- a lack of economic competition ---- the good or service that they provide and a lack of viable substitute goods..

Bleeding after oral surgery can usually be stopped ---- keeping steady pressure ---- the surgical site for the first hour..

As regards breast changes, our definition ---“normal” varies ---- age and experience..

For decades presidents have been coming ---plans to deal with the fact that one day the world will run ---- its key source of energy: oil..

Philosophers have debated the relation ---thought and emotions ---- at least two millennia. .

Severity of autism ranges ---- those who are mute and have no functional behaviour ---individuals with high IQ scores..

Most companies would prefer to concentrate ---domestic rather than foreign markets because of their greater familiarity ---- their own environments..

An Indian drug company has offered to supply an anti-AIDS drug ---- sufferers in developing countries ---- less than one-twentieth of the standard cost in the West..

People who travel ---- airlines all have stories ---how bad the experience is when things go wrong..

Scientists have studied the health status of native people in the South Pacific ---- decades, and have noted the explosion of diet-related disease ---- the area..

Economists take pride ---- the sophisticated statistical techniques ---- which they rely to analyze phenomena such as growth rates, inflation, unemployment, trade and fiscal practices..