题干
I cannot listen to both of you at the sametime. Please talk one after another.
A：at times
B：at one time
C：at a time
答案(点此获取答案解析）
C
I cannot listen to both of you at the sametime. Please talk one after another.
A：at times
B：at one time
C：at a time
O2+HbCO ，37 ℃时，该反应的平衡常数K="220" 。HbCO的浓度达到HbO2浓度的0.02倍，会使人智力受损。据此，下列结论错误的是 ( )