资本主义萌芽出现的表现方式（）

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 the 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 bccome too crowded. They move down to the low land. Sometimes they move all the way the seadide,and many of them are killed when they fall into the sea.

Recently, scientists have studied the migration of 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 know 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.

小题1:.Most animals move from one place to another at a certain time to _____

A.give birth        B.enjoy warmer weather   C.find food more easily

小题2:The fish called “salmon”spends a long time in____

A.salt water        B.rivers                 C.fresh water

小题3:The mice in northern Europe move when_____

A.they give birth   B.the place gets too crowded

C.they haven’t enough food

小题4: The lobsters move_______.

A.to the fresh water   B.at a certain time  C.to find more food

小题5: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.

______是世界上最长、开凿最早的人工河；我国水量最大的河流______；含沙量最大的河流______；汛期最长的河流______；结冰期最长的河流______．

下腔静脉的直接属支是

A．肝门静脉
B．肝静脉
C．脾静脉
D．胃左静脉
E．胃右静脉

为了比较水和煤油的比热容，小明在家里做了如下实验：在两个相同的塑料瓶甲和乙内分别装入______相同、初温都是室温的水和煤油，在瓶口扎上气球，将它们一同浸入热水中，如图所示（1）通过观察______，来判定瓶内水和煤油温度的高低． 

（2）要使两球膨胀的大小相同，应对______ （选填“甲”或“乙”）瓶加热的时间长些．  

（3）此实验表明______的比热容大些．

冶炼B钢时，加B的顺序应该是（）。

A．Al→Ti→B

B．B→Al→Ti

C．Ti→Al→B