Should this also accept the past tense: "They sent their fried chicken recipe"?
They send out their fried chicken recipe
They send their fried chicken recipe == Is the same==
How do you send it if it doesn't go out?
=Come on Duo Lingo= have a look here.
Why don't they just say "kirim", the common word for "send", instead of bothering with all those extra letters of "mengirimkan"?
In daily conversation, some native would only say kirim. But it sounds a bit weird though. And in formal language, it is not accepted.
me-...-kan is used to highlight / emphasize that some things are in the process.
So can I understand that "They are sending their fried chicken recipe" should be correct too?