当空气中的氧含量低于（）％，简易防护面具不能使用。A.15 B.18 C.20 D.

二次函数f（x）=x²-2x+5，x∈[0，3]，最大值是______；最小值是______．

女性，30岁。因重度哮喘急性发作住院治疗缓解，平时亦有哮鸣音存在。请问出院后最有效和推荐长期应用的抗炎剂是（）。

A.抗生素

B.泼尼松

C.酮替芬

D.沙丁胺醇

E.吸入糖皮质激素

When the people in the area heard the news that a rare vase which was used by an emperor

during the Ming Dynasty was buried somewhere near their homes, they all went out ___ it.  [ ]

A. to search  

B. to look at  

C. in search for  

D. in search of

He was no longer _______ by the news of his mother’s death.

A．affected

B．effected

C．effected on

D．affected to

简述社会经济责任观的主要内容。