not…until等于if？

not…until不等于if not.

直到…才

Not until they pointed out my fault to me did I realize it .

直到他們指出了我的錯誤，我才意識到。

if not:

如果不；不然的話

Do you want that cake? If not, I'll have it.

你要那塊蛋糕嗎？不然我就要了。

For what are we born if not to aid one another ?如果我們不能互相幫助，活在世上干么？