Unit Five/Focus on: Causal Analysis
Chapter 13 Dinosaurs: Why They Disappeared
Several theories have been propod about why the dinosaurs disappeared from the face of the earth. In recent years one popular theory propos that climatic changes caud the dinosaurs to become extinct. This climatic change theory says that millions of years ago the climate of the world gradually became colder. As the earth slowly became colder, fewer plants were able to grow. The cold weather finally resulted in a vere shortage of food for the dinosaurs. As you probably know, most of the dinosaurs were vegetarians, and they depended on plants for their food supply. In summary, then, the disappearance of the dinosaurs was caud directly by a shortage of plants to eat, and indirectly by a change in the climate. Many scientists still believe that the climatic change theory best explains why the dinosaurs disappeared. This theory argues that the dinosaurs disappeared gradually--slowly--as the earth became colder and as their food supply dwindled.恍然大悟什么意思
三杯茶读后感
经济法课件Today there is new evidence for the theory that the dinosaurs did not disappear gradually, b
ut that they disappeared quickly and suddenly. This theory is known as the asteroid theory. It states that a huge asteroid, or perhaps a comet, hit the earth about 65 million years ago. When this comet or asteroid hit the earth, it caud a huge dust cloud. The huge dust cloud covered the whole earth and blocked out the sun for months. Since there was no sun for many, many months, most of the plants on earth died. The dinosaur's food supply was destroyed in a period of months.
While this asteroid theory is not new, what is new is the evidence for the theory. Until recently there was no evidence that an asteroid or a comet had hit the earth 65 million years ago. What happened recently was that scientists found large amounts of a rare earth element called iridium all over the world. This iridium was found in layers of the earth that are 65 million years old. The iridium was found in the same layers where the bones of the last dinosaurs were found. The element iridium is very uncommon, in fact, rare, on the earth.
杞蓉胶囊It is an element, however, that is more often found in space. Scientists speculate that this iridium was brought to earth 65 million years ago when a comet or asteroid hit the earth.
The comet or asteroid theory explains two things: (1) It explains the larger amounts of the rare element iridium found in the 65-million- year-old layers of earth, and (2) it explains why the dinosaurs disappeared from the earth.创新口号
Today scientists continue to debate the two theories: the climatic change theory and the asteroid theory. In the future evidence may be found that supports a totally new theory of why the terrible lizards died out.
Predicting the end of a story: Stating the possible results
1.it’s a cold and snowy night. A man and a woman are traveling in a car. They are driving along a winding mountain road. It is difficult to e out the windshield becau the snow is falling so hard and becau one of the windshield wipers is broken. Suddenly there is a sharp curve in the road. The man steps on the brakes hard. What happens?
2.2. It's the last half of a championship soccer game. The team from France has scored t
大姐用针不用线hree goals. The team from Venezuela has scored three goals. The score is 3 to 3. Suddenly the forward on the French team gets the ball. He takes it toward the French goal. He's clo to the goal. He kicks the ball. What happens?
3.A man is walking along the river. Suddenly he hears a young boy calling for help. The man looks toward the river and es a young boy. The boy is trying to stay on top of the water. The man is not a good swimmer. What happens?
4.You and your friend Bob are sitting in the movie theater waiting for the movie to begin. Bob is telling you about his girlfriend Donna. He says that Donna told him that she had to visit a friend who is sick this evening. Then you and Bob e Donna and another man walking down the aisle. They are looking for ats. They don't e Bob and you. Bob suddenly stands up and says to you, "Excu me for a minute." What happens?
慰藉的读音5. You are waiting in line at the bank to cash a check. You hear a woman scream. You turn around and e three men with guns in their hands and masks on their faces. One of the men yells for everyone to lie down on the floor. You lie down on the floor quickly. Wha
t happens?
Listening Factoid 1
Dinosaurs are generally believed to have been very large animals and it's true that some of them were incredibly large. One dinosaur, believed to have been the largest dinosaur ever, is called ismosaurus. Seismosaurus literally means "earth shaker." This animal was between 100 and 120 feet long and weighed about 89 tons. To give you some idea of how big ismosaurus was, let me tell you that an American football field is 300 feet long. Consider that the African elephant weighs between six and ven tons. This means that ismosaurus was about 13 to 14 times heavier than an African elephant. It's not surprising that his name means "earth shaker"!
