I don't remember where I bought it.
- Ya no me acuerdo de dónde lo compré.
I don't know where he comes from.
- No sé de dónde viene.
Tom knows which way the wind is blowing.
- Tom sabe de dónde sopla el viento.
I would like to see the trees from which you picked these apples.
- Quisiera ver los árboles de donde agarraste estas manzanas.