(单选题)

What step is essential to the traditional production of flu vaccine?

A.Manufacturers implant the vaccine into ordered chicken eggs.

B.Scientists identify the exact strain soon after a flu pandemic starts.

C.Public health measures are taken as an important pandemic-fighting tool.

D.Viruses are deadened and made clean before being put into vaccine use.

参考答案：D

参考解析：

细节理解题。根据第二段最后一句话“Virus from the eggs’ innards gets killed and processed to remove egg proteins and other contaminants before being packaged into vials for fall shipment.” 可知生产者生产疫苗在春末和夏季。首先由自动的机器将病毒注射到鸡蛋中，然后将充满流感病毒的粘性物质从中吸出。将鸡蛋内脏中的病毒杀死后加工，取出鸡蛋蛋白和其他的杂质，然而装入小瓶，用于秋季时的运输。所以在投入疫苗使用之前，病毒会被消灭干净。故选D。

知识点：阅读理解四选一英语专业基础知识阅读理解教师招聘-小学英语