某炼钢电炉的烟气组成如下表，其标准状态下干烟气的密度为（）。 A.1.359kg/m

Everything that humans hear is in the form of waves (波).Just as the eye sees light wares in the form of colors, the ear and the eye Curs these different waves into signals that the brain (大脑) can make sense of.

The ears and brain have an Amazing amities to recognize（识别）particular sounds. For example, a mother often can tell when her baby is crying even if there are other crying babies in the same room. This is because the sound of her baby’s cry has special meaning to her and the brain has recorded is importance.

The ability to recognize sounds improves with experiences. As the brain receives information about sounds from day to day, it stores the information in its memory. When the brain hears new sounds, it gives meaning to them based on the information already in the memory. This is why certain words or songs can make a person happy. Often it is not the words or songs themselves that cause this feeling. The sounds are connected to happy memories for that person.

After hearing process controlled by the brain is to decide where a sound is coming from. One ear is usually closer to the source (来源) of a sound than the other ear is. Sound waves are stronger when they reach the ear that is closer. They also reach the closer ear first. The brain recognizes these differences and uses them to decide the location of the source of the sound.

小题1:Which of the following shows the normal hearing process of a mother hearing her baby crying?

a. The ears receive the sound waves.

b. The mother recognizes her baby’s cry.

c. The ears turn the sound waves into signals.

d. The baby’s cry ravels in the form of sound waves

e. The brain connects the signals to the information in me memory.

A．d-a-c-b-e

B．d-a-c-e-b

C．a-d-c-b-e

D．a-d-c-e-b小题2: Certain words or songs can change tarpon’s moods mainly because of his         .

A．lifestyle

B．personality

C．experiences

D．hobbies小题3:According to the last paragraph, It will be the most difficult for a person who has lost the hearing in one ear to tell         .

A．where the source of a sound is

B．how loud a sound is

C．when a sound starts to appear

D．what makes a sound小题4:What is the best title for this passage?

A．Human Brain’s Amazing Facts

B．Human Hearing Characteristics

C．How to improve Hearing

D．How Do Humans Hear

马克思指出：“如果把商品体的使用价值撇开．商品体就剩下一个属性，即劳动产品这个属性。”这句话表明：商品的本质属性是价值，价值的本质是

A．商品的交换价值

B．商品的效用

C．商品的个别价值

D．体现着商品生产者之间的社会经济关系

在下列物质中，硫元素为+4价的是

A．H₂S

B．SO₂

C．S

D．H₂SO₄

眶上切迹（）

A.位于眶上缘中点

B.位于眶上缘内、中1/3交界处

C.位于眶上缘外侧

D.位于眶上缘内侧

E.以上都不对

小序