题目

下列关于生物膜系统的叙述正确的是（    ） A．生物膜系统包括细胞膜、细胞器膜、核膜、视网膜等生物体内的各种膜结构 B．各种生物膜的化学组成和结构完全相同 C．细胞内化学反应都在生物膜上进行，生物膜为酶提供大量的附着位点 D．细胞膜在细胞与外部环境进行物质运输、能量交换和信息传递过程中起决定性作用阅读理解。We know that many animals do not stay in one place. Birds, fish and other animals move from one place to another at a certain time. They move for different reasons: most of them move to find food more easily, but others move to get away from places that are too crowded.When cold weather comes, many birds move to warmer places to find food. Some fishes give birth in warm water and move to cold water to feed. The most famous migration (迁移) is probably the migration of fish, which is called “salmon”. This fish is born in fresh water but it travels many miles to salt water. There it spends its life. When it is old, it returns to its birthplace in fresh water. Then it gives birth and dies. In northern Europe, there is a kind of mouse. They leave their mountain homes when they become too crowded. They move down to the low land. Sometimes they move all the way to the seaside, and many of them are killed when they fall into the sea.Recently (近来), scientists have studied the migration of a kind of lobster (龙虾). Every year, when the season of the bad weather arrives, the lobsters get into a long line and start to walk across the floor of the ocean. Nobody knows why they do this, and nobody knows where they go. So, sometimes we know why humans and animals move from one place to another, but at other times we don’t. Maybe living things just like to travel.1. Most animals move from one place to another at a certain time to _______.A. give birth B. find food more easilyC. enjoy warmer weather D. find beautiful places2. The fish called “salmon” spends a long time in ______.A. fresh water B. riversC. salt water D. its birthplace3. The mice in northern Europe move when _______.A. they give birth B. they haven’t enough foodC. the weather is bad D. the place gets too crowded4. What is the main idea of the passage?A. Animals move to find food more easily.B. The migration of the fish called “salmon” is the most famous migration.C. Sometimes we know why and how living things move from one place to another, but sometimes we don’t.D. Living things move from one place to another because they like to travel.