average number of defects

例句：

1. 1. The average temperature in the city is around 20 degrees Celsius.
   这个城市的平均温度大约是20摄氏度。
2. 2. The average salary for a manager is $50,000 a year.
   经理的平均年薪是5万美元。
3. 3. The average lifespan of a human being is about 75 years.
   人类的平均寿命大约是75岁。