問題詳情

42 題至第 46 題  Sometimes the normal processes of cell growth, death, and regulation get completely deranged. Cells aretransformed and begin robbing their neighbors’ blood supply, like vampires. They defy normal limitations ongrowth, multiply unceasingly, and then invade space reserved for others. They refuse to die on schedule. These arecancer cells, and they are responsible for about two million new cases of various cancers that occur every year inthe United States, and over half a million deaths. One out of five people in industrialized countries will die ofcancer, most of them from tumors that originated in a lung, breast, prostate gland, colon, or rectum. And except fora few very clear instances such as lung cancer caused by smoking or exposure to certain chemicals and radiation,no one knows exactly why.Unlike smallpox or malaria, cancer is not a distinctive disease with a single cause. It arises from various kindsof mutations in a cell’s DNA. Some mutations occur naturally. In the course of an average human lifetime, billionsof trillions of cell divisions take place. Given this huge number of replications, mistakes are bound to happen. Theymay result in a disadvantageous change for the organism; some may even spawn cancers. More often, mutationsand cancers are prompted by external causes.
42 Which of the following statements best characterizes cancer cells?
(A) They are mostly found in human blood.
(B) They can grow and proliferate continuously.
(C) They can be transformed into vampires.
(D) They can defy the process of mutations in a cell’s DNA.

參考答案

答案：B
難度：適中0.463235
統計：A(14),B(63),C(23),D(27),E(0)

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