“Why didn’t she come to the meeting yesterday？” “I’m not so sure. She ______ ill.”

A．should be

B．should have been

C．must be

D．might have been

机体获得人工主动免疫的方式是（）

A.注射抗体

B.注射类毒素

C.注射抗毒素

D.注射胎盘球蛋白

E.折射丙种球蛋白