Insert the prepositions wherever necessary. 1. thermodynamics deals the conversion mechanical energy thermal energy. 2. the production heat means may be illustrated the phenomenon friction. 3. a heat engine is a machine transforming heat mechanical energy. 4. to transform energy any its numerous forms heat is a comparatively simple process. 5. case the ideal reversible process, there is no change the quantity available energy. 6. no change a system bodies that takes place itself can increase the available energy the system. 10. make up dialogues on the following topics using the introductory and connective words.