Dave's ESL Cafe's Student Discussion Forums

[jasonlulu_2000]

If I didn't know better, i would say you're my daughter, Cordelia.

What does "didn't know better" mean? Why does the author use a negative way?

2. She's dead as earth.

I cannot find this phrase in any dictionary? Is it a fixed phrase?

Thanks

[Bluegum]

"If I didn't know better" means if I would have thought so, except that I know it isn't true.
I have never heard of "dead as earth" before.