Adults can easily survive on seven to eight hours' sleep a night, (4)_______teenagers require nine or ten hours.

American folk music originated with (1)________ people at a time when the rural population was isolated and music was not (2)________ spread by radio, records, or music video. It was (3)_______ by oral traditional and is noted for its energy, humor, and emotional impact. The major source of early American folk songs was music from the British Isles, but songs from Africa as songs of the American Indians have significant part in its heritage. Later settler from other countries also contributed songs. In the nineteenth century, composer Steven Foster wrote some of the most enduringly popular of all American songs, (4)_________ soon became part of the folk tradition. Beginning in the 1930s, Woody Guthrie gained great popularity by adapting melodies and lyrics and supplying new ones as well. In the 1950s and 1960s, singer – composers such as Peter Seeger, Bob Dylan, Joan Baez continued this tradition by urban’ folk music. Many of these songs deal (5)________ important social issue, such as racial integration and the war in Vietnam

They don't like interruptions or (2) ______changes of schedule. Punctuality is very important so you should arrive on time for appointments.

When the weather is cold, it is not very much fun to (1) ______a bus. People have to stand at a bus-stop for minutes or even hours. They talk about the bus and (2) _______about the weather. Most of them feel cold. Some have to drink coffee to stay warm. Traveling by buses (3) _______ pollution, but people often would rather drive their cars. Many people are not used to the bus schedules, and they do not like to wait. On the other hand, many people have been (4) ______the bus every day for many years. They are used to it. They say the bus has been coming on time every day, and they have never been late for work. In (5) _______, they do not need a parking place in all that time. Buses are very convenient when you are used to them.

Higher education also provides a competitive edge in the career market. We all know that in the economic times we are living in today, finding jobs is not guaranteed. The number of people unemployed is still relatively high, and the number of new career (1) ......... isn’t nearly enough to put people in jobs they are seeking. As a job seeker, you’re competing with a high number of experienced workers (2) have been out of the workforce for a while and are also seeking work. (3) , when you have a higher education, it generally equips you for better job security. Generally speaking, employers tend to value those who have completed college than those who have only completed high school and are more likely to replace that person who hasn’t (4) a higher education. Furthermore, some companies even go so far as to pay your tuition because they consider an educated (5) to be valuable to their organization. A college education is an investment that doesn’t just provide you with substantial rewards. It benefits the hiring company as well

(3)______ , when you have a higher education, it generally equips you for better job security.

These days young people give up when there's the (4)________ argument.

There are many sources of pollution in our modern world. At present, the most severe sources are acid rain, car exhaust fumes and oil spills. Factory chimneys give (1)______ smoke that contains sulfur dioxide and nitrogen oxide. These gases combine with the moisture in the atmosphere to (2)______ sulfuric acid and nitric acid. When it rains, these acids dissolve in the rain and turn it acidic. Acid rain is thought to be the worst pollution problem of all. It has (3)_____ aquatic life by turning many lake into lifeless bodies of water. In these areas, there is no limestone in the rocks to neutralize the acid rain naturally. One remedy is to pump limestone into the acidic lakes. (4)_______ , it is not possible to do this on a large enough scale to save all the lakes. Car exhaust fumes contain carbon monoxide and lead which are highly poisonous. In big cities, the exhaust fumes build (5)______ and pose a health hazard to human beings. Pollution of the sea by oil threatens marine life. Much of the oil comes from ships that clean their fuel tanks while at sea. Offshore oil wells also discharge vast amounts of oil into the sea. Pollution of the sea can also be caused by oil spills. An oil spill may occur as a result of accidents involving oil tankers.

As health and education are the State's (4)_____ , they affect the country's finances. So in developing countries health and illiteracy continue to be the problem. The unwieldy growth of population leads to the problem of housing and sanitation.

Another popular scene involves an automatic feeding machine brought to the assembly line (3)______ workers need not interrupt their labor to eat. The feeding machine malfunctions, hurling food at Chaplin who is strapped into his position on the assembly line and cannot escape.

Two–way (1)_____ depends on having a coding system that is understood by both sender and (2)_____ , and an agreed convention about signaling the beginning and end of the message.