变态反应的本质是（）
A.特殊免疫应答
B.异常免疫应答
C.正常免疫应答
D.非特异免疫应答
E.回忆应答
参考答案：B
-Turn off the TV, Jack.___________ your homework now?
-Mum, just ten more minutes, please. [ ]
A. Should you be doing
B. Shouldn't you be doing
C. Couldn't you be doing
D. Will you be doing
桥式起重机大车啃轨如何判断？其产生的原因是什么？造成的影响和危害有哪些？
