một lần khi mà ngay khi một khi 
once like: một khi → →
wir hatten zwar weder Ozean noch Sandstrand, aber dafür ein angenehmes Klima. ☊ 
Chúng con không có đại dương cũng chẳng có bãi cát, nhưng có một khí hậu thật dễ chịu. ☊ (Lektion 55, Nr. 783) Ich habe eine schwerwiegende Reklamation. ☊ Tôi có một khiếu nại nghiêm trọng. ☊ (Lektion 125, Nr. 2466) This was one aspect of her character he hadn't seen before. ☊ aspect ☊
They wanted to move to a warmer climate. ☊ climate ☊
complaint (that...): a complaint that he had been unfairly treated ☊ complaint ☊
You'll like her once you get to know her. ☊ get ☊
to launch an appeal/an inquiry/an investigation/a campaign ☊ launch ☊
We didn't know how we would cope once the money had gone. ☊ once ☊
The water is fine once you're in! ☊ once ☊
There'll be plenty of opportunity for relaxing once the work is done. ☊ opportunity ☊
Cool, loose-fitting clothes are practical in a hot climate. ☊ practical ☊
satisfy sb/yourself (that)...: Once I had satisfied myself (that) it was the right decision, we went ahead. ☊ satisfy ☊
She's planning to return to work once the children start school. ☊ work ☊