题目内容
（请给出正确答案）
A．viruses are known to cause cancer in animals
B．at present, human cancer is not believed to be contagious (传染的)
C．there are many known causes for the transformation of a normal cell to a cancer cell
D．results of experiments on plants and animals do not vary greatly from species tn species
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更多“Cancer should be considered to…”相关的问题
A.build up
B.make up
C.stand for
D.con to
A．they are innocuous agencies
B．they are the causative agents of most human cancer
C．they seem to be infections to many people
D．they are generally thought to be relevant to most cancer in man
The possibility that a virus causes human cancer is indicated by ______.
A．the fact that viruses have been known to mutate
B．the fact that a cancer-immune individual may lose his immunity
C．the fact that production of human cancer cells might be due to a genetic factor
D．the fact that man is host to many viruses
Paragraph 1 shows that subjects in the ugly room tend to be______.
A．less patient
B．less considerate
C．more enthusiastic
D．more confident
Because Max had lung cancer, he stopped ______ .
A．to smoke
B．smoke
C．smoked
D．smoking
According to the context, the word in "oncogenes" in para. 2 means ______.
A．genes that can kill cancer
B．genes that will lead to leukemia
C．viruses that can kill AIDS
D．genes that will lead to cancer
Which is the best title for this passage？
A．The Possibility of Life on the Mars
B．Future Conditions on the Mars
C．The Mars and the Earth
D．A Study of the Climate of the Mars
Under what conditions will the formation of cancer begin？
A．When a chromosome breaks apart neat an oncogene and its control functions fail.
B．When people drink too much and are easy to get tired.
C．When people smoke too much and are difficult to get to sleep.
D．When people eat too much petroleum-based products.
Dr. Jason decided to help his students by______.
A．collecting used textbooks
B．writing a concise textbook
C．selling second-hand books
D．making public speeches
