I'm not sure if it's acceptable to share links, but here a document I wrote with a short overview of when and where we use -ING form:
https://docs.google.com/document/d/1SgDdqSj1Iu-qlqnGAPcacDJBmLkFTC0hmOKFWwrbRYk/edit?usp=sharing
If the link doesn't work, send me a message and I'll send it to you.
My best,
-Axl
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