单项选择题
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
单项选择题 Which of the following can be the best title of this passage （）
单项选择题 30（）
单项选择题 29（）
