Here are sample answers for the paraphrasing exercise:

1. According to Jacques Cousteau, the activity of people in Antarctica is jeopardizing a delicate natural mechanism that controls the earth's climate. He fears that human activity could interfere with the balance between the sun, the source of the earth's heat, and the important source of cold from Antarctic waters that flow north and cool the oceans and atmosphere ("Captain Cousteau" 17).
2. During the twenties lawlessness and social nonconformity prevailed. In cities organized crime flourished without police interference, and in spite of nationwide prohibition of liquor sales, anyone who wished to buy a drink knew where to get one. Musicians like Louis Armstrong become favorites, particularly among young people, as many turned away from highly respectable classical music to jazz. One of the best examples of the anti-traditional trend was the proliferation of young "flappers," women who rebelled against custom by cutting off their hair and shortening their skirts (Yancey 25).
3. The use of a helmet is the key to reducing bicycling fatalities, which are due to head injuries 75% of the time. By cushioning the head upon impact, a helmet can reduce accidental injury by as much as 85%, saving the lives of hundreds of victims annually, half of whom are school children ("Bike Helmets" 348).
4. Matisse paintings are remarkable in giving the viewer the distinct sensory impressions of one experiencing the scene first hand. For instance, "The Casbah Gate" takes one to the walled city of Tangier and the Bab el Aassa gateway near the Sultan's palace, where one can imagine standing on an afternoon, absorbing the splash of colors and the fine outlines. Even the sentry, the bowaab vaguely eyeing those who come and go through the gate, blends into the scene as though real (Plagens 50).
5. How much higher skyscrapers of the future will rise than the present world marvel, the Sears Tower, is unknown. However, the design of one twice as tall is already on the boards, and an architect, Robert Sobel, thinks we currently have sufficient know-how to build a skyscraper with over 500 stories (Bachman 15).