1. Why the stars will flash flash it?

　We see stars sparkle, this is not because the stars change their brightness, but with the atmosphere, blocking the.

　Across the atmosphere between us and the stars, when the starlight through the atmosphere, they will receive the impact of atmospheric density and thickness. The atmosphere is not absolutely transparent, its transparency will be different according to the density difference. Therefore, we look at the stars on the ground through it, you'll see the stars as if flashing the same again.

　2. Why do people yawn?

　When we feel tired, the body has generated a lot of carbon dioxide. When the excess of carbon dioxide, it is important to increase the oxygen needed to balance the body. Because these residual carbon dioxide, would affect the functioning of our body activity, then the body will issue a protective response, so e on playing yawn.

　Yawning is a kind of deep breathing movements, it makes us more than usual, sucked into oxygen and emit carbon dioxide, but also do it to eliminate the role of fatigue.

　3. Why are snakes able to walk without feet?

　The snake's body there are many scales, which is the outermost layer of their body armor. Scale is not only used to protect the body, can also be their "feet."

　Snake crawling forward, the body will be showed S-shaped. And every one in the S-shaped outside of the scales will tilt to help the snake move forward to seize the uneven road surface. The scale of muscle co-ordination with the snake, and can push the body forward in crawling, so the snake can move without legs呀!

　4. Why do sunflowers bloom is always toward the sun,

　Sunflower chrysanthemum stems the following places, contains something called "plant growth hormone," substances. This material is accelerating function of reproduction, but it has a repulsive optical activity, when confronted with the light, they will go to the backlight side.

　Therefore, when the sun rises, sunflower stems will immediately hide backlight side to go on the whole plant looks toward the direction of the sun was bent.

　5. Why does a person old hair will be white?

　Our hair had something called "melanin" in substance, the more melanin the more black hair color. The melanin *** all, yellow or white hair will be issued. Humans in old age, the body's various functions will gradually decline, pigment formation will be less and less, so the hair will gradually bee white ah!

　6. Why is Firefly will shine?

　Firefly will be light because in the end of their abdomen are light-emitting devices, light-emitting device filled with a number of quality and light-emitting light-emitting phosphorus-containing enzymes, so that can be issued a flash of fireflies flash of light.

　The purpose of firefly light, in addition to lighting, there are mating, warning, trapping and so on. This is also a munication tool for them, different types of fireflies light-emitting means emitting frequency and the color will be different, they like to take this to convey a different message.

　7. Why are hungry will cluck call?

　She was hungry and rolling will be called, it is because the food prior to eating fast to digest finished, although the empty stomach, but will continue to secrete gastric juice the stomach. At this time the contraction of the stomach will gradually expand inside the liquid and gas will be welling up, resulting in rolling sound.

　Next time should no longer stomach the embarras *** ent of cuckoo called ah! Because this is a normal physiological actions do.

　8. Why does an ostrich does not fly?

　Body type of a large ostrich class, but they do not fly overhead, and ah! This is not because their wings do not work, but their feathers are too soft, wings too *** all, not fit for flying. In addition, the ostrich muscles developed, sternum flat again, and on the flight did not help.

　Ostriches live in Africa, due to the long living in desert areas, the body in order to adapt to the environment, they gradually evolved into what it is.

　9. Why is not perishable and canned food inside?

　Luncheon meat, lobster sauce dace, tomato sauce, canned beans . are delicious food, they can be stored for a long time are not easily deteriorate. This is because canned food is sealed, the bacteria can not enter.

　People in the manufacture of canned food, when the canned air in all out, and then seal it. In the absence of air case, even if some bacteria inside the food from being contaminated, they can not survive or breed ah!

10. Why did the baby will be born just been crying?

　When you are making all sorts of new born babies cry, not because they feel unhappy, but they are the first port Dakoutaikou to breathe the air it!

　When the baby to leave her mother at birth the body, they suck the air into the first port will be up to the throat, which will violently hit vocal cords, so that vocal cords vibration, and then issued a similar crying sound.

　11. Why is the tail of lizards are constantly bouncing off behind that?

　In order to protect themselves, many of Xi Tang also facilitate protective coloring deceive the public; while some lizards when attacked, the tail will be a result of intense muscle contraction caused by broken down. Based on the tail broken off there are still part of the nerve is alive, it will continue to bounce, thus dispersed the enemy's attention in order to escape. Do not think that the end of their lives so, in fact, just a few months, the tail will grow back and continue to live.

　12. Why is the squirrel's tail particularly large?

　Do not look relaxed rat tail! Squirrels jumping in the trees, while its tail is playing a very useful role. It can make squirrels in the trees be balanced when jumping to avoid falling injuries. In addition, this tail significantly better in the winter, the function of the protective, tightly around the squirrel's body, both convenient and practical.

　13. Why does a person's thumb can not have one or three?

　Most people have five fingers, while the length of the fingers are different. However, there is no one noticed that in addition to the thumb, other fingers have three, while only two thumbs alone do? The original, it is in line with the other four sessions means. If three, then the thumb would appear there is no power that it can not bring heavy objects; if only one, it can not easily with the other four fingers with the grasp things!

　14. Why was not I do not feel itchy and scratching yourself?

　As someone scratch their own, we will feel itchy, and kept laughing; However, when scratching his own time, not only do we not laugh, but also do not feel itchy. Based on our minds have been prepared, the brain will be issued a "no danger" message, nerves has also e to relax, so they will not laugh and feel itchy in!

　15. Why is sea water are mostly blue, green?

　Look to the sea, in many also found that water showed blue, green. However, when you picked up the water, you can only see it like the old days of water-like, transparent colorless. The original, the sea itself, with our daily e into contact with water, there are no major difference is transparent. We have seen the green, in fact, is the water absorption capacity of light arising out of the phenomenon. Only green water can be absorbed, and thus reflected out; as deeper water, the green light was absorbed, the sea looks became blue.

　16. Why goose bumps?

　Our skin long with fine hair, and each one has an erection under the hair pore muscle, when the subject nerve stimulation (for example: anger, fear, cold, etc.), the body temperature will decline, while the vertical hair muscle contraction will be thus making hair erected to form a goose bumps. In addition to the role with insulation, such a physiological body system would also make the animals more than it actually seems to deter the enemy.

　17. Hippocampal which goes by the father's birth?

　Almost all animals are also the next generation of female reproduction, but the hippocampus is different, it is out by a male birth. In the male hippocampus has a belly like a Kangaroo "parenting bag" bag of the hatchery, the female male Hippocampus hippocampus will routed to the hatchery egg sacs. After the male hippocampus on to take up the responsibility of breeding, after about three weeks, the *** all hippocampus would pop up from his father's body.

　18. Why are the leaves changed color?

　The leaves change color because of its inherent chemical substances - chlorophyll related. When autumn es, the time during the day is shorter than that in the summer, but temperatures are relatively low, the leaves stop manufacturing chlorophyll, therefore, the remaining nutrients transported to the storage of trunks and roots. The green leaves in the absence of chlorophyll, at the same time, other chemical pigments and thus apparent, so we can see more colors such as yellow and brown leaves.

　19. Why are there leaves?

　Autumn is ing when the leaves on the evaporation of moisture more than the summer, but the roots are less absorbent than the summer. In order to reduce the moisture loss of trees, the stem cells began to form a separate layer, to be pletely detached from the leaves of nutrients, the separation layer will separate the leaves and tree trunks, leaves to fall off.

　20. Why did the whale will spray?

　Whales are mammals one, but it does not nose shell nose, nose length in the head. It lives in water breathing with the lungs, can save a lot of one-off air, do not often go to the surface ventilation. But when it es to the surface of the water ventilation, it will be used for nasal breathing, while breathing in vitro associated water spray is issued by the giant wave caused by the pressure.