I need help...
1. In the sentence "Dare ga kore wo shita ka (to) iite kudasai"(Please tell me who did it.), do I have to use "ka to" or just "ka"?
2. If I want to add the particle "de" to "nani", could it be "nani de" or "nan' de"?
Yes, "Nani de" I guess is supposed to make it a little more formal than nande to mean "by what means" or "how," or for the speaker to show super clearly they didn't want to ask "why."
Like Nan(i) de Tokyo ni ikimasuka?
Still, based on Tsuguri's question regarding the current situation, nande/nan de is much more normal for a beginner.