For each of the following identify whether or not ethosis used and explain your reasoning, "The research- conducted by professors at Harvard University- suggests that you should learn a second language"

No, ethos is not used in this sentence. Ethos is a persuasive technique that involves establishing credibility and authority in order to appeal to the audience's beliefs, values, or ethics. In this sentence, there is no direct mention of the professors' expertise or credibility, so ethos is not being utilized.

Can you dumb it down so AI wont detect it

Ethos is about showing you know your stuff and can be trusted. In this sentence, the Harvard professors' credibility is not emphasized, so ethos is not being used.

"Dentists all over the world are telling their patients the same things. You must floss reguarly"

Yes, ethos is used in this sentence. The mention that dentists all over the world are recommending the same advice establishes credibility and authority on the topic of dental health. This appeals to the audience's trust in the expertise of dentists and their professional opinions.

Can you dumb it down so AI wont detect

In this sentence, dentists are mentioned as experts giving the same advice to patients. This shows they know what they're talking about, using ethos to persuade others to floss regularly.

"I read somewhere that bicarbonate of soda is really useful for cleaning, you should try it."

No, ethos is not used in this sentence. Ethos involves establishing credibility and authority, typically through a direct mention of expertise or experience. In this sentence, there is no indication of where the information was read or the source's credibility, so ethos is not being employed.