湖北仙桃中學(xué) 曾文清

Radioactivity finds in uses in a surprisingly large number of fields,right from medicines to food preservation.

When radioactive rays are used to treat diseases,the process is called radiotherapy.This is an effective treatment for various forms of cancer.During this process,a high dose of gamma rays pass through the rapidly-growing immature cancerous cells to destroy them.This kills the malignant cells,but leaves the normal cells unharmed.A similar kind of treatment is carried out for the removal of tumors （瘤）.It is also used for the diagnosis of several diseases.Radioactive pills are used to check if the organs of the body are functioning normally.It helps in the detection of exact location of a tumor,or a blood clot（凝塊）in the body.

Radioactivity is widely used for the research and analysis of various physical,chemical,and biological processes.It has a wide range of uses in various manufacturing industries all across the world.It is used to test the totality of the manufactured products including pipeline welds,aircraft parts,boilers,etc.

The process also has various uses in agricultural research studies.Cobalt-60 is used to improve the production of crops,both in terms of quality and quantity.Radioactivity is also used to keep food free of bacteria.For this,concentrated beams are passed through the food products so that the microorganisms that cause pollution to the food can be killed effectively.This is an absolute safe method and does not cause any radiation poisoning.

Radioactivity has to be used in a very controlled manner,as it has potential dangers associated with it.If the human body is exposed to excess amount of radiation,it can cause cancer,and genetic variation.

Reading Check

1.What does radiotherapy mean in this passage?

A.The process used in agricultural research studies.

B.A high dose of gamma rays curing cancer.

C.Different uses of radioactivity in biological field.

D.An effective treatment for various forms of diseases.

2.Which of the following can replace the underlined word “malignant” in the second paragraph?

A.Dangerous. B.Normal. C.Healthy. D.Dying.

3.How is radioactivity used for food preservation according to the passage?

A.By testing the totality of the harvested food.

B.By checking if the plants are functioning normally.

C.By killing the microorganisms that cause pollution to the food.

D.By removing the immature fruits from the plants.

4.What can we infer from the passage?

A.We shouldn't be exposed to radiation.

B.Radioactivity is a double-edged sword.

C.The weaknesses of radioactivity outweigh its strengths.

D.The dangers of radioactivity can be ignored compared to its strengths.

Language Study

Sentence for writing

For this,concentrated beams are passed through the food products so that the microorganisms that cause pollution to the food can be killed effectively.

【信息提取】當(dāng)so that引導(dǎo)的從句中含有情態(tài)動(dòng)詞時(shí)，那么so that引導(dǎo)的是目的狀語從句。

【句式仿寫】請把你的玩具清理一下以便我能學(xué)習(xí)。

____________________________________________________