Farmers are extremely busy during the harvest.

农民在收获季节里十分忙碌。

IVF clinics can be extremely busy.

IVF的门诊是极其忙碌的。

The post office was extremely busy.

邮局相当的繁忙。

I'm extremely busy.

我非常忙。

So this day has been extremely busy.

所以这天确实是非常忙。