人类创造的自然语言和人工语言：（）
A.是人类意识的物质外壳
B.是人类的主观意识
C.是意识的客观内容
D.既非物质，也非意识
参考答案：A
I regret _____ hard at school, or I would have succeeded in passing the exam.
A．not to work
B．having not worked
C．to have not worked
D．not having worked
血浆游离Hb正常参考值是（）
A.<0.04g/L
B.<0.02g/L
C.<0.08g／L
D.>0.10g／／L
E.>0.15g/L
