惑星 わくせい かん航行 こうこうじゃなかったです
waku seikankōkōjanakattadesu

Noun
Desu Copula

The polite, past negative form of 惑星間航行

1. Interplanetary travel wasn't.; It wasn't interplanetary travel.

Past/Perfective
Negative
Polite
Casual Register