on average造句

On average each report requires 1,000 hours to prepare.
准备一份报告平均需要1,000小时。

Every tonne of coal contains, on average, 30 kilograms of nitrogen.
每吨煤平均含30公斤氮.

We received 20 calls a day on average.
我们平均每天接到二十个电话.