Answer:
20. whose: Relative Pronoun
13. happy: Adjective
14. who: Relative Pronoun
15. which: Relative Pronoun
23. that: Relative Pronoun
18. small: Adjective
26. colorful: Adjective
27. to: Preposition
26. inside: Preposition
29. silly: Adjective
30. whom: Relative Pronoun
31. bumpy: Adjective
32. tall: Adjective
33. after: Preposition
Step-by-step explanation:
20. John, whose mum I know, is my friend.
13. Mary owns a happy dog.
14. I know a guy who plays poker very well.
15. The house in which I live is huge.
23. The people that you know are all funny.
18. There is a small bed in the room.
26. A colorful butterfly flew by.
27. I'm going to Rome next week.
26. There is a pocket inside the jacket.
29. Harry is a really silly dog, but I love him.
30. The woman to whom I spoke is my teacher.
31. Be careful, there is a bumpy road ahead.
32. A tall tree casts a nice shadow.
33. I will rest after the finals.
Whose mean of which.
Who is used when it refers to a subject, namely the noun who refers to is performing the action, or involved in it. In the example, the guy plays poker, we use who to refer back to the guy since he is the one playing poker.
Whom refers to an object of an action. In the example, the woman is spoken to (object) and she is not doing the speaking (I am speaking to her). In American English whom is used only in formal enviroments.
Prepositions, when used as such, are always accompanied by nouns, groups of nouns, adjectives+nouns etc.
Adjectives qualify nouns, groups of nouns. They can also follow the verb to be and work as propositional adjectives (propositional with an o, not prepositional. Propositional means sentential, something which has to do with sentences). E.g.: My hair is beautiful.