Cannot is formal, while can't in informal.
"Cannot" and "can not" are interchangeable, but when you are asking question for example:
"why can't I...", you can also say "why can I not..." (which is more formal), but you can't say "why cannot I..."
The check can represent Mama’s longing for a better life
Question:<em> Which kind of clause are the words in bold?</em>
I think your answer is,