She swore blind that she had never seen him before.

【swear】她一口咬定她以前从未见过他。

And many sandwich aficionados swear blind that the biggest improvement to any bought sandwich is a layer of ready-salted crisps.

许多三明治爱好者坚决声称，与任何买来的三明治相比，它最大的改进就是加了一层即食咸薯片。