题目

解释生物进化的原因，目前人们普遍接受的是达尔文的自然选择学说，以下关键词能正确概述自然选择学说内容的一组是（ ）①自然发生 ②物种不变 ③过度繁殖 ④环境污染 ⑤生存斗争 ⑥遗传、变异 ⑦适者生存． A . ①②③⑦ B . ④⑤⑥⑦ C . ①③④⑤ D . ③⑤⑥⑦ 答案：DPassage 23 (2012 佛山，B)       Everyone knows that chickens lay eggs (产卵). Most people know that all the other birds do as well. But have you ever though about other animals that lay eggs? They include bees,snakes and some sea animals.      When a mother lays eggs,many more babies can be born at once,or in a few days,because there is very little development inside the parent.Animals that do not lay eggs often have fewer babies. Animals lay many eggs because other animals may eat the babies. However,even though some of their babies are eaten,they will still have some more to continue their family.      Some animals that lay eggs do not take care of their young. Turtles come on to the beach and dig (挖) holes. Then they put their eggs in the sand and leave. A turtle mother can lay as many as 150 eggs.When the babies come out of the eggs,they must find their own way to the ocean. They must learn how to live on their own. Many young turtles get eaten by other animals.     Most eggs have an outside shell (壳) that keeps the growing animal inside safe. The eggs shell also keeps the young animals from drying out. After the animal is fully developed,it comes out of the egg- The animal grows bigger and bigger. Then it can have its own young.1. Which animals lay eggs?① Snakes.② Turtles.③ Camels.④ Bees.⑤ Chickens.   A. ①③④⑤   B. ①②③⑤   C. ①②④⑤   D. ②③④⑤2. Why do animals lay many eggs?   A. Because other animals may eat their babies.   B. Because they use their eggs for food.   C. Because they want to have fewer babies.   D. Because they want to eat their babies.3. What do we know about turtles?A .They don't look after their babies.   B. Baby turtles hate their mother.   C. Other animals can’t eat turtle babies.   D. Turtle babies can’t take care of themselves.4. Egg shells can be used to       .   A. make eggs more beautiful   B. make eggs more tasty   C. let the young animals dry   D. protect the young animals5. The passage is probably from       .   A. a newspaper        B. a science book   C. a sports magazine   D. a storybook