开抽负器为什么要先开开工抽负器。

简述传统零售企业进军B to C电子商务的核心优势。

阅读理解。

     Many animals recognize their food because they see it. So do humans. When you see an apple or a piece

of chocolate you know that these are things you can eat. You can also use other senses when you choose

your food. You may like it because it smells good or because it tastes good. You may dislike some types of

food because they do not look, smell or taste very nice. Different animals use different senses to find and

choose their food. A few animals depend on only one of their senses, while most animals use more than one

sense.

     Although there are many different types of food, some animals spend their lives eating only one type. The

giant panda (大熊猫) eats only one particular type of bamboo (竹子). Other animals eat only one type of food

even when given the choice. A kind of white butterfly (蝴蝶) will stay on the leaves of a cabbage, even though

there are plenty of other vegetables in the garden. However, most animals have a more varied diet (多样化饮

食). The bear eats fruits and fish. The fox eats small animals, birds and fruits. The diet of these animals will

be different depending on the season.

     Humans have a very varied diet. We often eat food because we like it and not because it is good for us. In

countries such as France and Britain, people eat foods with too much sugar. This makes them overweight,

which is bad for their health. Eating too much red meat and animal products, such as butter, can also be bad

for the health. Choosing the right food, therefore, has become an area of study in modern life.

1. We can infer from the text that humans and animals _____.

A. depend on one sense in choosing food

B. are not satisfied with their food

C. choose food in similar ways

D. eat entirely different food

2. Certain animals change their choice of food when _____.

A. the season changes

B. the food color changes

C. they move to different places

D. they are attracted by different smells

3. We can learn from the last paragraph that _____.

A. food is chosen for a good reason

B. French and British food is good

C. some people have few choices of food

D. some people care little about healthy diet

( )的缝面上出现的剪应力很小，使坝体能保持较好的整体性。

A．斜缝分块
B．纵缝分块
C．错缝分块
D．横缝分块

在区域经济合作中有（）三方面的因素起着最重要的作用。

A.合作主体

B.合作客体

C.合作对象

D.合作效益

D.合作意图