Can someone please help me with this one?

Im the following sentence, what is the complete subject . an old friend of mine is in the hospital

“i didn't know that cheshire cats always grinned; in fact, i didn't know that cats could grin.” “they all can,” said the duchess; “and most of 'em do.” “i don't know of any that do,” alice said very politely, feeling quite to have got into a conversation. “you don't know much,” said the duchess; “and that's a fact.” what is the effect of the short sentences on the dialogue? they make the dialogue smooth and serene. they make the dialogue lively and humorous. they make the dialogue formal and elegant. they make the dialogue into a song.

How are key ideas refined with clear and concise language in the selection “what are our demands? ” what purpose does this selection serve?