Question

请问英语高手这句话怎么理解？

I know how to operate a computer. ___, I thought I did until I saw this one.
A. That is B. That's it C. That's that D. That's life
答案是A, 请问这句话怎么翻译，怎么理解?

Answer 1

我知道如何操作电脑，我是说，我一直是这样想的，直到我看到这台电脑。