The past participle of the verb "lecture" is "lectured."
"Since she knew what the lecture was about" in the first sentence is replaced by the participle phrase "Knowing what the lecture was about" in the second sentence."Knowing" is the present participle of the verb "to know". Here it works like an adjective describing "she". She was a "knowing" woman. She was a "knowing-what-the-lecture-was-about" kind of woman.
Being is the present participle. The past participle is been.
"Leaving" can be both a present participle and a past participle. As a present participle, it functions as part of the progressive verb forms (e.g., "I am leaving"). As a past participle, it is used in perfect verb tenses (e.g., "I have left").
Presenting is the present participle of present.
Presenting is the present participle of present.
The present participle of "walk" is "walking."
The present participle of "choose" is "choosing."
The present participle of "clean" is "cleaning."
The present participle of "lead" is "leading."
The present participle of "swear" is "swearing."
No, "have been" is not a present participle. It is the present perfect tense of be. Being is the present participle of be.