How are you?[ ]
A. Fine, thanks.
B. I'm ten years old.
C. OK.
答案：A
—My father is ill in hospital, I’m looking after him. —___________.
A．Not at all
B．I’m afraid
C．I’m sorry to hear that
D．It doesn’t matter
局部粘膜抗感染免疫的最重要的Ig是
A．IgMB．IgGC．IgDD．IgEE．SIgA
