Your teacher will for a fact i know that so dont use it twice
Your tone
Let's look at the other choices first. Your credibility is your ability to be believed as trustworthy in regards to the subject. Whether you're talking to a group of teenagers or professional adults, your credibility doesn't change. Your clarity also should not change based on the audience because you want to be clear in your message at all times. Also, your purpose should be the same no matter the audience. The only thing that would change is your tone. The way you approach a crowd of teenagers would vary greatly from the way you'd approach a room of professionals.
The PAST PROGRESSIVE TENSE indicates continuing action, something that was happening, going on, at some point in the past. This tense is formed with the helping "to be" verb, in the past tense, plus the present participle of the verb (with an -ing ending): I was riding my bike all day yesterday.
