メタン けい炭化 たんか水素 すいそでしょう
metankeitankasuisodeshō

Noun
Desu Copula

Expresses probability in a polite manner ("probably…") of メタン系炭化水素

1. Methane-based hydrocarbons; Probably methane-based hydrocarbons

Polite
Presumptive
Conjecture