发绀伴杵状指（）
A.大量气胸
B.法洛（Fallot）四联症
C.休克
D.缩窄性心包炎
E.贫血
参考答案：B
It is required that more attention _____ the education of the children in poor areas. [ ]
A. should be paid to improve
B. be paid to improving
C. should be paid to have improved
D. be paid to have improved
引起种实霉烂的病原主要为（）。
A.菌类
B.库内高温
C.种子不成熟
D.种子含水量高
