average ligand number

例句：

1. 1. The average temperature in winter is around 5°C.
   冬天的平均温度大约是5°C。
2. 2. The average life expectancy for women in their 30s is 8 years.
   30岁女性的平均预期寿命是8年。
3. 3.The average income of a doctor is much higher than the average salary.
   医生的平均收入远高于平均工资。