Since lightning was probably significant in the formation of life, understanding it might help us ________ life itself

Double-star orbit ..............

The flag of the original colonies may or may not have been ............ by Betsy Ross during the revolution.

If the oxygen supply in the atmosphere ......... replenished by plants, it would soon be exhausted.

The exam results could .............. your career.

In 1975, according to the national center for health statistics, the average life expectancy for people born during that year ............... 72.4 years

The extent to which an individual is a product of either heredity or environment ............ but several theories have been proposed

Civil engineers had better .............. to use steel supports in concrete structures built on unstable geophysical sites

Goods for sale at ............... prices.

Jane Addams had already established full house in Chicago and ............ her work in the women's suffrage movement when she was awarded the Nobel prize for peace.

Because .............. food is as nutritious for a baby as its mother's milk, many women are returning to the practice of breast feeding.

A ............. is a person who searches for valuable minerals.

In ancient times and throughout the middle ages, many people believed that the earth ........... motionless.

Often a team of engineers is ..............

Nitrogen must be .......... with another element such as hydrogen or oxygen to be useful in agriculture or industry

A .............. mountaineer reached the top of the Himalaya last week

Anyone reproducing copyrighted works without permission of the holders of the copyrights .............. breaking the law.

Oscillatona, one of the few plants that can move about, ............ a wavy, gliding motion.

Supersonic transport .......... the Concorde will probably be widely accepted as soon as problems of noise and atmospheric pollution are resolved.

I need to earn ........... money, but then I lost my job.

Your mistakes in composition are similar ............. his

................ poetry is more enjoyable when it is read aloud.

I didn't enjoy this book on how to succeed in business. It wasn't very.................

Starfishes and sea urchins, members of the echinoderms or spiny skinned animals, are particularly ........... because of their unusual structures

The practical and legal implications of euthanasia, the practice of causing the death of a person suffering from an incurable disease, are so controversial .......... it is illegal in most countries.

All the cereal grains ........... grow on the prairies and plains of the United States.

Three dangerous criminals escaped ................. prison yesterday.

One way to inform the public about factories that pollute the environment is through ............ programs on TV.

All of them are freshmen, ............................ whom come from countryside.

To relieve pain caused by severe burns, prevent infection, and treat for shock, ...............

Every country ........... a national flag

Without alphabetical order, dictionaries would be ............... to use.

The corals can be divided into three groups, two of which ............. extinct

A vacuum will neither conduct heat nor ..............

Traditionally, the flag is .......... in the morning and taken down at night.

John F. Kennedy was the youngest president of the United States and ........... to be assassinated.

Green and magneta are complementary colors located opposite each other on the color wheel, ................

................. thought was given, but all was not approved.

I was shocked ........... the news of the crashed plane.

Optical fibers ............. to deliver laser light.