<25D8> Sound travels over 14 times faster through steel* than through air. If you need to quickly signal someone standing on a metal bridge, bang* on a steel pipe!

　　<25D8> Most researchers say that tomatoes are really fruits, not vegetables.

　　<25D8> A Japanese explorer named Maomi Uemura was the first man to reach the North Pole alone, April 29, 1978, after his eight-week journey.

　　<25D8> The number of bacteria* in a quart of (1.136 liter) soil from your backyard garden is 30 times greater than the population of the world.

　　<25D8> Steamboat Geyser*, located in Yellowstone National Park* of the United States, is the most powerful geyser in the world, and can shoot super-hot water 300 feet (90 m) in the air.

　　<25D8> The first modern traffic light was put to use in Cleveland, Ohio in 1914.

　　<25D8> Every year, plants make and store 10 times the amount of energy that people use.

　　<25D8> About 80 percent of the earth’s animals are insects!

　　<25D8> It took 55 years before the telephone, invented in 1820, was put to use in society.

　　<25D8> When high-speed trains pass each other they must slow down or they will break their windows. The passing trains produce a low-pressure area between them that can actually pull the glass out of the frames.

　　<25D8> Manhole* covers, the lids that cover sewers*, are always round. Why? The round cover rests on a lip* that is smaller than the cover so it can’t drop through the opening. A square* or rectangular* cover, no matter how it was made, could fall through.

　　<25D8> The most drought* resistant* tree is the baobab tree*. It stores 35,900 gallons (161,550 liters) of water in its trunk for later use.

　　(SD-Agencies)(Difficulty: senior)

　　西红柿是蔬菜还是水果？声音的传播速度是在空气中快，还是在钢中快呢？第一个独自到达北极探险的是谁？你知道世界上最抗旱的树是什么吗？最大最壮观的间歇泉的名字是什么，又在哪里？

　　哇！这么多有趣的科学问题，答案嘛，都在下面啦！