Probably if you tend to confuse these two sounds, something like 'Wery vell' comes out, right?

可能你会把这两个发音弄混，然后就说成了‘Wery vell’，对吧？

" I am not mistaken, " said Krum coldly. " I walked past that sign for several years, I know it vell."

“不会错的，”克鲁姆冷冷的回答，“我看着这个标志长大的，绝不可能记错。”

Maybe two 'V's or two 'W's, or perhaps you're just mixing the two things and saying something like 'wery vell' instead of 'very well'.

可能会说成两个‘V’或两个‘W’的音，还可能就是把两个弄反了，说成‘wery vell’，而不是‘very well’。