“~nagara” is use for combining 2 actions into one sentence

Example 1
Drinking Beer - Bi-ru o (nomu)nonde imasu
Watching Television - Terebi o (miru)mite imasu
I am drinking beer while watching television - Biru o nominagara, terebi o mite imasu

Meaning : Bi-ru (Beer), Terebi (Television)

Example 2
Singing a Song - Uta o (utau)utatte imasu
Walking - (Aruku)Aruite imasu
I am singing a song while walking - Uta o utainagara, aruite imasu

Meaning : Uta (Song), Utau (Sing), Aruku (Walk)

Normal Form
Kau (Buy)
Kaku (Write)
Oyogu (Swim)
Hanasu (Talk)
Matsu (Wait)
Hakobu (Carry)
Nomu (Drink)
Uru (Sell)

Special Words
Kiru (Wear)
Miru (See / Watch)
Suru (Do)

~nagara
Kainagara
Kakinagara
Oyoginagara
Hanashinagara
Machinagara
Hakobinagara
Nominagara
Urinagara

Special Words
Kinagara
Minagara
Shinagara

See, Its simple. ;)

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