つく
点く
tsuku

Godan Verb (ku)

1. to be lit (of a lamp, burner, etc.); to catch fire; to ignite; to start burning

Intransitive
Usually Written in Kana
Related to 付く
木造もくぞう建築けんちくぶつがつきやすい。
mokuzōkenchikubutsuwa higa tsukiyasui.
Wooden buildings catch fire easily.
Godan Verb (ku)

2. to be turned on (of a light, appliance, etc.); to come on

Intransitive
Usually Written in Kana
あかりがいちばんちゅうついている。
tomoriga hitobanjū tsuite iru.
The lights have been burning all night.