TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (disclosed): The new aromatic compound is obtained by reacting a dihalogenated compound of formula: X-R-X, a compound having nitrogen-containing aromatic ring structure, or its derivative(s), and a dihydroxy compound of formula (I) (e.g. 1,4-(4-hydroxy-benzoylbenzene) and 1,4-bis(4-hydroxyphenyl)benzene). Preferred Compound: The aromatic compound is preferably of formula (3).P'=group of formula (b, c or d);andH'02=P' or R.    TECHNOLOGY FOCUS - POLYMERS - Preferred Polymer: The polyarylene copolymer preferably has a structure of formula (4). The copolymer further consists of an aromatic-sulfonic-acid-containing repeating unit of formula (5).Y'=-CO-, -SO2-, -SO-, -CONH-, -COO-, -(CF2)a-, or -C(CF3)2-;Z=single bond, -(CH2)b-, -C(CH3)2-, -O-, or -S-;Ar=aromatic group having substituent chosen from -SO3H, -O(CH2)cSO3H, and -O(CF2)cSO3H;c=1-12;j,h=0-10;andk=1-4. Preferred Definitions:    R=divalent organic group including nitrogen-containing aromatic ring structure derived from compound(s) chosen from pyrrole, thiazole, isothiazole, oxazole, isoxazole, imidazole, imidazoline, imidazolidine, pyrazole, 1,3,5-triazine, pyridine, pyrimidine, pyridazine, pyrazine, indole, quinoline, isoquinoline, tetrazole, tetrazine, triazole, carbazole, acridine, quinoxaline, quinazoline, indolizine, isoindole, 3H-indole, 2H-pyrrole, 1H-indazole, purine, phthalazine, naphthyridine, cinnoline, pteridine, carboline, phenanthridine, perimidine, phenanthroline, phenazine, phenarsazine, phenothiazine, furazan, phenoxazine, pyrrolidone, pyrroline, pyrazoline, pyrazolidine, piperidine, piperazine, indoline, isoindoline and quinuclidine, preferably 1,3,5-triazine, pyridine, and/or their derivatives.    EXAMPLE - (In g) 2,6-dichloropyridine (5.39), 2,2-bis(4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane (51.9), and potassium carbonate (27.7) were taken in a flask. Sulfolane (180 mL) and toluene (90 mL) were added and stirred after nitrogen substitution. The reaction liquid was heated and refluxed at 150 degrees C in an oil bath. Water produced by reaction was trapped, and toluene was removed. After increasing reaction temperature to 200 degrees C and stirring for 4 hours, 4,4'-dichlorodiphenylsulfone (31.4) was added and reacted for 4 hours. 4,4'-Dichlorodiphenylsulfone (14.8) was further added and reacted for 4 hours. Toluene (150 mL) was added and diluted after cooling the reaction liquid. Insoluble mineral salt was filtered, and the filtrate was poured into methanol (2.4 mL), and a product was precipitated. The precipitate was dissolved in tetrahydrofuran (300 mL) after filtration and drying, and poured into methanol (2.4 L) and reprecipitated. The precipitated white powder was filtered and dried, to obtain an aromatic oligomer (73.5) of formula (A) (AA is group of formula (aa), BB is group of formula (bb), q is 30), having a number average molecular weight of 12000. The obtained compound (9.06), 3-(2,5-dichlorobenzoyl)neopentylbenzenesulfonate (19.7), bis(triphenylphosphine)nickel dichloride (1.31), sodium iodide (0.22), triphenylphosphine (5.25), and zinc dust (7.84) were polymerized with N-methyl-2-pyrrolidone (19 ml) at 80 degrees C for 4 hours. The solidified substance was filtered and vacuum-dried, to obtain a polyarylene copolymer (22.7) having a number average molecular weight of 36000 and a weight average molecular weight of 130000. The copolymer (20) was reacted with lithium bromide (7.5) and N-methyl-2-pyrrolidone (160 ml), to obtain a sulfonic-acid-group-containing polymer (17) of formula (B) (r is 98.6, q is 24, s is 1.4) with a yield of 90%. The polymer had a number average molecular weight of 40000, a weight average molecular weight of 155000, and a sulfonic-acid equivalent of 2.22 meq/g. The polymer had proton conductivity of 0.317 S/cm at 90% relative humidity and 0.035 S/cm at 50% relative humidity, and excellent chemical stability.