Jeremy Crawford, in a tweet, wrote that a Moon Druid can speak the languages it knows while shaped as an Elemental because the Elemental can speak.
The Giant Elk can speak the "Giant Elk" language, so does that mean I can speak all the languages I know if I Wild Shape into one?
Then again, the Giant Elk is said to "Understands Common, Elvish, And Sylvan But Can't Speak Them". Does that mean I can speak all languages I know except these three?
Or can I only speak Giant Elk, because other languages include verbal components that the Giant Elk is incapable of reproducing?