参考答案

正确答案：B
解析：细节题型见第三段第三至五句：Continuing their careful tests，the doctors checked the effect of drugs against all the known subgroups of virus type A. None of them have any protection．This．then，was something new，a new influenza virus，against which the people of the world had no help whatever．(这些医生们继续他们细致的测试后，发现所有已知对A类病毒的附属亚病毒有疗效的药物对此种病毒均无效；因此这种病毒是种新型的流感病毒，世上还无药物能对人类抵抗这种病毒有所帮助)；因此B为答案。