[noun] + だ + けど/けれど/けれども
Note: けど is most casual, けれど is slightly more formal, けれども is most formal. Second clause may be omitted for implied meaning.
The ~けど structure is an informal conjunction used to connect two clauses, expressing contrast or contradiction. It is the casual counterpart of ~が and is used in conversation.
It is used at the end of a sentence without completing the second clause, leaving the implied meaning for the listener to interpret.
けれど is a slightly more formal version of けど, used in polite speech, while けれども is the most formal.