maggiesensei.com/2016/03/28/casual-contraction-dropping-%e3%81%84-i-%e3%81%a6%e3%82%93-ten-%e3%81%a8%e3%81%8ftoku/
Maggie Sensei explains casual Japanese contractions like てる (teru) for ている (teiru) and てん (ten) for ている (teiru), showing how native speakers actually speak versus textbook forms.
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