灯す

1. Origins, structure, and basic meaning

• Structure: 灯す is a transitive godan verb read ともす, meaning to light or kindle a lamp, flame, or other source of light.
• Basic usage: Use ランプを灯す for lighting one lamp and 多くの明かりを灯す for lighting many lights.
  • 暗くなったので、机の上のランプを灯しました。 describes lighting the lamp on the desk after it became dark; 祭りの夜には川辺で多くの明かりを灯すそうです。 reports that many lights are lit by the river on the night of the festival.

2. Common pitfalls and similar expressions

• ランプを灯す
  • を marks the lamp as the object being lit.
• 川辺で灯す
  • で marks the riverside as the place where the lights are lit.
• 灯すそうです
  • そうです presents the festival practice as information the speaker has heard.