Elimination reaction (E2)

[duchuy]

Homework Statement

Monomolecular or bimolecular reaction

Relevant Equations

x

Hey,
I have this equation in which I have to determine its reaction mechanism.

I managed to determine how we managed to obtain this the molecule in the picture above, but I don't understand the mechanism behind obtaining the second alkene. Thank you so much for your help, and sorry if the vocabulary is incorrect since I translated this from french.

 

[mjc123]

Are there any other hydrogens that could be abstracted by the OH^-?