I'm really confused with your edited document. Sometimes, even the same sentences, you edited in different ways and wonder which one is correct.<br />For example, in the following sentence, you edited it as follows<br /><br />...as concentration of phosphate increases, the significant adsorption of P to Zn makes the release of Zn<sup>2+</sup> to be limited."<br /><br />here since concentration of phosphate is singular, you used the verb as "increases"<br />but I think we should add "a" before concentration? is this correct or not?<br />as an example, ...as <strong>a</strong> concentration of phosphate increases, the significant adsorption of P to Zn makes the release of Zn<sup><span style="font-size: small;">2+</span></sup> to be limited."<br /><br />please let me know SOON. I need to submit this soon<br /><br />