"Ellas abren estos mensajes."
Translation:They are opening these messages.
I would translate that as: They open these messages.
For some reason, duolingo has started using continuous progressive present tense meanings as an equivalent to simple present tense questions, there's not a huge amount of difference between the actual meaning, but it's causing a lot of confusion to new learners.
Simple present tense:
ellos abren - they open
Continuous progressive present tense:
estan abriendo - they are opening
As you can see, they are opening, is not the same as they open, but duolingo is treating them as the same and I don't agree with it.
The most frustrating part of Duo using first one tense then the other, is that they don't always accept the choice we make?? That's just not right.