IF you want to take the exam in MAY but you cannot on 27, there will be an additional opportunity on the day after, 28.
In this case, you have to register for the 27, BUT indicate in the notes that you need to take it on 28.
IN THE NOTES, also indicate if you did not manage to read some (or all) papers in the B list. Please indicate the number of the papers that you did not read, for instance B1, B2, B4
To register, you have to use the esami webportal. You can reach it through this link ...
https://esami.unipi.it/esami2/elencoappelli.php?from=sappelli&docente=&insegnamento=principles+of+sustainable+development&cds=&cerca=
DO NO FORGET to fill in the excel SHEET, PLEASE DOWNLOAD the UPDATED one
You can find the new one in this page: https://elearning.ec.unipi.it/mod/page/view.php?id=24494