Answer:
Well, Technically all words can be used in an essay its honestly just how you say them, or use them. Most words that you should use is descriptive words AKA words that discribe something. More words to use are Symbols, symbols are very useful in essays even paragraphs, Stories, Pretty much anything.
Explanation:
The infinitive phrase in this sentence is to speak clearly, and it is used as a subject of the sentence. What/who is essential to being understood? To speak clearly.
Being faithful in God is probably the best response there
Air pollution is affecting the environment in negative ways.