Irrovocable letter of credit是什么?我想问这是一种什么付款方式吗?

Irrovocable letter of credit是什么?我想问这是一种什么付款方式吗? What letter is like twelve o'clock? letter letter 问:What letter is like twelve o' clock?答:_______________________________ what letter is like twelve o'clock?why?回答 what is the next letter?O T T F what is the last letter?J A S O N What is the letter A like twelve o' clock? Why is the-letter A like twelve o'clock?quick Why is the letter A like twelve o'clock 意思 Why is the letter A like twelve o'clock? Why is the letter A like 12 o'clock? why is the letter O like a pain? The word hour b____ with the letter h,not o Why is the letter O like a pain? here is a word.the letter Cis before L.U is after O and after L.the letter d is after U.the letter 1.O,O,T,T,F;( ).What's the next letter? A.:O B:S C:F