平均值定理

例句：

1. 1. The average temperature in winter is below freezing point.
   冬天的平均温度低于冰点。
2. 2.The team's performance was below average last season.
   这个队伍上个赛季的表现低于平均水平。
3. 3. The new product has a lower average cost than the old one.
   新产品的平均成本比旧产品低。