Answer:
20. Heat-thermal
21. Sound-audio
22. Form-morph
23. Book-bibliography
24. Earth-geography
Explanation:
A thermal relates to body heat. Like the thermals clothing holds body heat to provide warmth
A sound is an audio that can be recorded and played as on a CD
Morphing something is changing the shape or form ie from circle to square
A bibliography is included in essays/books to show the sources and where quotes came from
Geography is the study of Earth
