Usages of gagnleg
Góð orðabók er gagnleg þegar ég skrifa lengri texta.
A good dictionary is useful when I write longer texts.
Orðabókin er mjög gagnleg þegar ég skil ekki allt.
The dictionary is very useful when I do not understand everything.
Elon.io is an online learning platform
We have an entire course teaching Icelandic grammar and vocabulary.