Answer:
1. Riya borrowed a dress <u>from</u> me and lent it <u>to</u> her friend, Mary.
2. When I moved back <u>to</u> the city, things had changed considerably.
3. The burglar found the keys <u>under</u> the pot <u>on</u> the balcony.
4. Prabhu was hiding <u>behind</u> the door when his sister came looking <u>for </u>him.
5. My dog sat <u>on </u>my hat and squashed it.
Explanation:
Prepositions are words used to connect nouns, pronouns, or phrases to other words in a sentence and describe the relationship between them. These relationships are often logical or related to space and time. For example, some prepositions of space are <em>in, on, behind, underneath,</em> etc.
The phrase that is made up of a preposition and words connected to it (e.g. <em>to the city, under the pot</em>) is called a prepositional phrase.