Locate the prepositions in the following sentences and identify the nominals that follow them (noun phrases, pronouns, gerunds, or nominal clauses).
The canyon formed in a relatively short period of time.
We listened closely to what what the guide told us about the trail leading into the canyon.
Edit the following passage to eliminate redundancy and make it more precise by removing distracting and unnecessary prepositional phrases:
Plaque has almost become a household word in this country. It is certainly a household problem for most people. But even though everyone is affected by it every day, few people really understand the seriousness of plaque in their daily lives or the importance of controlling it. Plaque is an almost invisible sticky film of bacteria that in the case of all of us continuously forms throughout the day and night. Plaque germs are constantly multiplying and building up on the teeth. Any dentist will tell you that controlling plaque from forming is the single most important step to better oral health for people everywhere.