防止转化炉火嘴回火的方法是（）。
A．降低火嘴燃烧负荷
B．保持火焰喷头清洁完好
C．减少供风量
D．降低炉膛负压
参考答案：B
— I only heard of John,but I never met him.What is he like?
— ______________.
A．He is from America.
B．He speaks English well.
C．He is kind and strong.
D．He is my best friend.
ANCA阳性小血管炎常见的肾脏病理改变为（）.
A.毛细血管内增生性肾小球肾炎
B.系膜增生性肾小球肾炎
C.系膜毛细血管性肾小球肾炎
D.局灶性节段性肾小球硬化
E.局灶节段纤维素样坏死性肾小球肾炎或新月体性肾炎
