考博考试

【单选题】That a different component part of the vaccine is necessary is principally due to the variable change of ______.
A．virus
B．strain
C．antigen
D．immunization
网考网参考答案：C
网考网解析：
文章第二段指出“constant changes of antigenic specificity of the virus necessitate a different composition of the vaccine(疫苗)from one year to another”，即病毒抗原特异性的不断变化导致了疫苗组成年年不同。故答案为C。 document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>