飛(ひ)行(こう)機(き) hikoukiは waすぐ sugu見(み)え()な()く() mienakuなった natta。 The airplane quickly disappeared from sight. Literal Airplane [topic-は] quickly visible-not became. すぐ means 'immediately, right away.' 見えなくなった combines the potential/spontaneous 見える ('to be visible') with ~なくなる ('cease to') — a compact way to describe something fading from view without naming an active hider. airplanestransportation~なくなる (cease to)
飛(ひ)行(こう)機(き) hikoukiは waすぐ sugu見(み)え()な()く() mienakuなった natta。 The airplane quickly disappeared from sight. Literal Airplane [topic-は] quickly visible-not became. すぐ means 'immediately, right away.' 見えなくなった combines the potential/spontaneous 見える ('to be visible') with ~なくなる ('cease to') — a compact way to describe something fading from view without naming an active hider. airplanestransportation~なくなる (cease to)