Answer: (Just a few:-)Adjective clauses:
1. The room where the children sleep is large. (replace 'there')
2. The mailman who delivers our mail is old. (replace 'he')
3. (Tricky) The table of which I fixed the broken leg* is an antique. (awkward but follows the "rule" not to use that.) (replace 'its.)
Better: The table with the broken leg which I fixed is an antique.
Noun clause section:
1. Whoever is ready to work will be welcome.
2. You may be surprised by how much there is to be done.
3. The grand prize will go to whichever float has the best design and workmanship.
Explanation:
The idea is to replace one word--usually a pronoun-- in the second sentence with a relative pronoun (They look like interrogative pronouns: who, which, where, when.)
Then rearrange the words of the second sentence to create an adjective clause and insert the clause after the noun it modifies in the first sentence.