A. would have to leave their fingerprints for further investigations B. could easily escape conviction of guilt C. would have to submit evidence for their innocence D. could be convicted of guilt as well 参考答案:B 答案解析:[解析] 推理判断题。依据第二段可知DNA指纹鉴定使罪犯调查发生革命性的变化,它为调查员提供了新的强有力的工具来证明犯罪,而不仅仅是确定无罪(attempt to prove guilt,not ju
A. frequent B. frequented C. frequently D. frequency 参考答案:C 答案解析:除去as…as…部分,that引导的从句可以简化为wildfires do not occur______。空格处应填入修饰动词occur的副词,因此(C)选项frequently是正确答案。
第34题: [单项选择]PCR反应的基本过程是 A. 退火—DNA合成—变性 B. DNA合成—退火—变性 C. 变性—DNA合成—退火 D. 变性—退火—DNA合成 E. DNA合成—变性—退火 参考答案:D 答案解析:PCR即聚合酶链反应,基本过程:①变性。反应系统加热至95℃,使模板DNA双链解离。②退火。将温度下降至适宜位置,使引物与模板DNA退火结合。③延伸。温度上升至72℃,DNA聚合酶以dNTP为底物催化