主要结合于细胞表面的Ig是
A．IgA
B．IgD
C．IgE
D．IgG
E．IgM
参考答案：B
解析：IgD主要结合于B细胞表面，是识别抗原。
Fever is a _____ of many illnesses. So I suggest you take it seriously and see a doctor
as soon as possible. [ ]
A. message
B. symptom
C. label
D. clue
