问题 单项选择题 A1/A2型题

急性白血病易出现感染,这主要是由于 ()

A.贫血

B.继发性营养不良

C.成熟粒细胞缺乏

D.广泛出血

E.脾大

答案

参考答案:C

解析:白血病由于异常的克隆细胞增殖失控,致使白血病细胞在骨髓中大量增生积聚,正常造血受到抑制,由于骨髓是产生粒细胞的唯一场所,其正常造血受到抑制,产生的粒细胞减少,进而成熟粒细胞缺乏。临床上表现为感染。因此本题正确答案是C。

单项选择题
阅读理解

Broken rubber bands and flat tires requiring replacement could soon be a thing of the past.

French researchers have developed a new kind of rubber that can repair itself when broken.The new rubber is made from widely available materials including vegetable oil and a common industrial chemical.All the materials are considered safe to the environment and can be easily reused.

The best part is that the new rubber can be repaired and used again and again without losing its strength or ability or stretch.When cut, the rubber can be made new again, simply by pressing the two broken ends back together.

The product can be repaired at room temperature, around twenty degrees Centigrade;other self-healing materials require higher temperatures for repair.

Traditionally, rubber substances are made from huge molecules(分子)connected by strong chemical links, or bonds.The new rubber is made of smaller molecules.The molecules are linked together using hydrogen bonds.When connected in this way, the molecules act like one long molecule, forming what is called supramolecular networks(超分子网).When the rubber is cut, the molecules attempt to connect with whatever molecule is near them.When pressed together, the molecules are able to repair themselves at the molecular level, making the repaired rubber like new.

However, time is an important element in the process.If the broken ends are not brought together quickly, a repair is not possible.This is because molecules will form bonds with molecules on their own side.The inventors say the surfaces of the rubber can be repaired within a week of being separated.

The rubber is the creation of scientists at the Industrial Physics and Chemistry Higher Education Institution in Paris.The organization is part of France’s National Center for Scientific Research.The new material is described in greater detail in the research publication Nature.

小题1:According to the introduction, which of the following is NOT the advantage of the new rubber?

A.It can be made as easily as common rubber.

B.It is environmentally-friendly.

C.It can repair itself at room temperature.

D.It is made of smaller molecules.小题2:What does the 5th paragraph mainly tell us?

A.Why the new rubber is unique.

B.Why the new rubber can repair itself.

C.The new rubber is made from huge molecules.

D.The new rubber is different from the common rubber.小题3:If we want to know more about the technology of this kind of new rubber, where can we get the information?

A.In the researchers’ diary.

B.In a guide book.

C.In a research magazine.

D.In a newspaper.