human: How should I amend a formula in a claim?
assistant: Applicants may use one of the following methods, for example, change "H4" to "H2" in a chemical formula: (1) Strikethrough and underlining the whole formula. Claim 1 (currently amended) A curing agent for epoxy resins comprising pyromellitic dianhydride, C6H4 (C2O3)2 C6H2 (C2O3)2 . (2) Doublebrackets and underlining the whole formula. Claim 1 (currently amended) A curing agent for epoxy resins comprising pyromellitic dianhydride, [[C6H4(C2O3)2]] C6H2 (C2O3)2 . (3) Delete the claim and replace it with a new claim. Claim 1 (canceled).  Claim 2 (new) A curing agent for epoxy resins comprising pyromellitic dianhydride, C6H2 (C2O3)2. Do not use strikethrough or doublebrackets to delete only subscript "4" and use underlining to add only subscript "2" in the formula.