1. It's fascinating to observe how so many of the <b><i><u>concerns voiced</u></i></b> remain the same.<br/>-- It's fascinating to observe how so many of the noun verb<br/><br/>2. It's fascinating to observe how so many of the <b><i><u>concerned voice</u></i></b> remain the same.<br/>-. It's fascinating to observe how so many of the adj. noun verb<br/><br/>3. It's fascinating to observe how so many of the <b><i><u>concerns voiced</u></i></b> the same.<br/>-. It's fascinating to observe how so many of the noun verb<br/><br/>I think sentence 2 and 3 are grammatically correct. Am I right?