为了保证锅炉燃烧过程的正常进行,空气需要不断地被送入()内,并及时将燃烧产生的烟气引至炉外,所用设备为鼓风机和引风机。
A.烟火管
B.炉膛
C.对流管束
D.集箱
参考答案:B
It's the little boy ____ often helps others ____ wins the first prize. [ ]
A. who; which
B. which; that
C. who; that
D. which; which
关于短暂性脑缺血发作,未经治疗的患者,其预后下列哪一项是错误的()
A.1/3发展为脑梗塞
B.1/3发展为脑出血
C.1/3反复发作
D.1/3自行停止
E.还有部分合并冠心病