胃溃疡出血的粪便颜色一般是
A．浆色便
B．淡黄色便
C．柏油样便
D．黑色便
E．鲜红色便
参考答案：C
--- Haven't I told you that I like the beef well done?
---Yes, but I _____ it longer than I usually do.
A．was cooking
B．will cook
C．cooked
D．had cooked
参与黏膜局部免疫的抗体是（）
A.IgA
B.IgG
C.IgM
D.IgG
E.IgE
