单项选择题
1. The concept of hypoxia means
A、Reduced oxygen saturation of hemoglobin
B、Reduced oxygen partial pressure of inhaled gas
C、Low blood oxygen content
D、Decreased oxygen binding capacity
E、Insufficient tissue oxygen supply or utilization
点击查看答案&解析
A. 
和
的两种单色光，先后照射同一种金属均能产生光电效应。已知金属的红限频率为
，测得两次照射时的遏止电压
，则这两种单色光的频率有如下关系（ ）
A.
B.
C.
D.
