ちょう音速 おんそく旅客 りょかく でしょう
chōon soku ryo kakukideshō

Noun
Desu Copula

Expresses probability in a polite manner ("probably…") of 超音速旅客機

1. Supersonic airliner, probably.; It will likely be a supersonic airliner.

Polite
Presumptive
Conjecture