average of relatives

例句：

1. 1. The average temperature in the city is 20 degrees Celsius.
   这个城市的平均温度是20摄氏度。
2. 2.The average income of a doctor is much higher than that of a lawyer.
   医生的平均收入远高于律师。
3. 3. The average life expectancy for women born in the 1950s is 78 years old.
   1950年代出生的女性的平均预期寿命为78岁。