1.It appears that the earth is the only planet that we know harbors life.
2.It is clear that the primitive magnetic south-pointing instrument appeared very early in China as a result of the knowledge people gained over long years of labor.
3.There are two important ways a cell can harvest energy from food: fermentation and cellular respiration.
4.There have been many mass extinctions throughout the history of the Earth, the most famous of which is probably the extinction that finally saw the end of the dinosaurs reign on the Earth 65 million years ago.
5.If a computer can be made complex enough, it can be as creative as a human being.
6.Today, a large number of transgenic animals have been produced worldwide for use in both basic and applied research.
7.Different from biologic warfare which attempts to kill, bioterrorism thrives on public fear, potentially immobilizing or demoralizing a population.
8.Computer-assisted decision support programs integrated with systems that cover each stage of the drug ordering and delivery process provide the most powerful prevention tools.
9.Dense tropical rainclouds distort the au flow aloft much as rocks distort the flow of a stream, or islands distort the winds that blow over them, but on a horizontal scale of thousands of miles.
10.We do not realize how much we depend on the earth's gravity until we are deprived of it, when our feet no longer stay on the ground, we float around in the air and the slightest touch may send us drifting off in the opposite direction.
11.Then there came the two major advances in the medicine.
12.There is no consensus among scientists that salt causes high blood pressure.
13.Short-term memory is best during the morning, about 15 percent more efficient than at any other time of the day.
14.Rainbows are formed when sunlight passes through small drops of water in the sky.
15.Rockets have found application for the exploration of the universe.
16.Statistics show it's likely that civilizations, if spread evenly throughout the universe, are about 1000 light years from each.
17.The moon is so far from the earth that it takes it a month to revolve around the earth, while man-made satellites, which are closer to the earth, can make a complete revolution in a few hours.
18.Depression not only keeps people dispirited, but also is a killer that directly interferes with the normal activities of the human immune system.
19.Atmosphere acts as a shield against harmful radiation and space debris.
20.It is pointed out by a UN report that if human destruction of their living space is not effectively stopped, apes such as gorillas, chimpanzees and orangutans will totally extinct in at most 50 years.