what do you think of the car i bought yesterday?
1,showing off; the addressee is a close friend or peer of the addresser.
2,asking for information; the addressee is an expert on cars,the addresser really needs his/her opinion.
this reflects cp in that the speaker and hearer agree to coopearte in a conversation initiated by the question above.
Your hat is very beautiful.
this sentence reflects pp in that it makes the receiver feels good,which is elaborated by Lakoff.