Usages of ~ttae
계단을 올라갈 때 조심해요.gyedaneul ollagal ttae josimhaeyo.
Be careful when going up the stairs.
친구를 만날 때 사진을 찍어요.chingureul mannal ttae sajineul jjigeoyo.
I take pictures when I meet a friend.
Elon.io is an online learning platform
We have an entire course teaching Korean grammar and vocabulary.