【完成句子】The average lightning strike is more than 3 miles long and can travel at a tenth of the speed of light. Ball lightning, the rarest and most mysterious form, derives its name from the small luminous ball that appears near the impact point, moves horizontally, and lasts for several seconds.One form of lightning that __________ is ball lightning.

【完成句子】Did you know that before 1950, hurricanes had no names? They were simply given numbers. The first names were simply Alpha, Bravo, Charlie, etc. but in 1953, females names were given because of the unpredictability(不可预知) factor of the storms. In 1979, realizing the sexist(性别歧视的) nature of such names, the lists were expanded to include both men and women.The main consideration of using males and females’ names for hurricanes is __________.

【概括大意】The key to gardening with kids, says Patti Kraemer-Doell, family garden coordinator at the New York Botanical Gardens, is “Letting them experience it themselves. We have tried to guide them, but not tell them to put the sunflowers here and the tomatoes there. The emphasis is on developing their imagination and their appreciation for being out in the garden.”The main idea of this paragraph is__________.

【完成句子】Lightning is generated when electrical charges separate in rain clouds, though processes are still not fully understood. Typically, positive charges(正电荷) build at the cloud top, while the bottom becomes negatively charged(负电荷的). In most instances of cloud-to-ground lightning, the negatively charged lower portion of the cloud repels negatively charged particles on the ground’s surfaces, making it become positively charged. The positive charge on the ground gathers at elevated points.In most cases of cloud-to-ground lightning, the ground’s surface__________.

【概括大意】If you are tired of making vague excuses for another dull summer at home, here is a thought to lift your spirits. You do not need anything so radical as winning a lottery(彩票) to finance a trip to Europe. A student identity card that can be obtained for a few dollars from the Council on International Educational Exchange entitles(给予、授权) you to discount tickets (打折机票) on certain charter flights to London and Paris, as well as reduced admission to many museums, cinemas, and musical events. Once in Europe, you can stay at approved youth hostels for about two dollars a night. So don’t give up your hopes of becoming an international traveler.The main idea of this paragraph is__________.

【完成句子】As the sunflowers grow, put a hay fence around them for protection and stake if necessary. Plant morning glories or sweet peas around the base of each sunflower, and they will grow up the stems, eventually forming a roof over the top. By summer’s end, kids will have a sunflower house to play in.When autumn comes, children can__________.

【概括大意】They always complained(抱怨) more or less justly, that their parents are out of touch with modern ways. They also blamed that their parents always have a final say. And the young felt that their parents do not trust their children to deal with crises. Besides, they dissatisfied too much murmurs of their parents about certain problems and the lack of sense of humor in dealing with the problems, at least in parents-children relationships.The main idea of this paragraph is__________.

【填句补文】Scientists have learned that the sense of pain is made up of both chemical and electrical signals. ________. Scientists also have learned that the nervous system sends two different kinds-of pain messages to the brain: one very fast, the other slow.

【填句补文】Posture. A good posture makes you feel better about yourself. ________. This makes breathing more difficult, which in turn can make you feel nervous or uncomfortable.

【填句补文】The Caribbean Islands form a chain that separates the Caribbean Sea from the rest of the Atlantic Ocean. ________. Many of the islands were formed by the eruption(爆发) of ancient volcanoes(火山)．Others are low-lying coral islands that gradually rose from the ocean.