✔ 最佳答案
Image of ethanedioic acid is shown below :
http://www.sigmaaldrich.com/content/dam/sigma-aldrich/structure1/132/mfcd00002573.eps/_jcr_content/renditions/mfcd00002573-medium.png
In the absence of C=C double bond, ethanedioic acid does NOT have geometrical isomers (cis- trans- isomers). There is only one form of ethanedioic acid molecule. In other words, cis-ethanedioic acid and trans-ethanedioic acid DO NOT EXIST.