収穫 しゅうかく逓減 ていげんじゃありませんでした
shūkakuteigenjārimasendeshita

Noun
Desu Copula

The polite, past negative form of 収穫逓減

1. Was not diminishing returns.; Was not decreasing returns.

Past/Perfective
Negative
Polite
Terminal Form
Economics