Hello again, Dr. Joo - With regard to first question, I would not add "the" - you don't need it, and in fact here you're talking about MNPs in general, yes? Given that, it's better to leave "the" out.<br /><br />Second, I couldn't find the phrase "exposure of MNPs to aquatic organism".&nbsp; I did see, in the schematic diagram Task 2,&nbsp;"exposure of MNPs to aquatic environment." If this is what you're referring to, in this case because this is a phrase not in the text but in a table-like setting,&nbsp;the article&nbsp;would be optional.&nbsp; However, in Task 1 we have "extraction of MNPs from the model products," and over in the other column I added "an" before&nbsp;"aquatic" under Module 2, you could add&nbsp;an article here, too&nbsp;- "exposure of MNPs to an aquatic environment" to be&nbsp;consistent.&nbsp; &nbsp; Rebecca TDE