why is 'savoir' followed by 'comment' here? In normally isn't in most of the examples.
There might not be a difference in the pronunciation (although in many French accents the vowel in "sais" will sound more like the vowel sound in the English word "air"), but "c'est tu ouvrir ...." is not a correct sentence. It literally translates as "It is you open ...."
I would also like to know why 'comment' is necessary along with savoir in this case.
I have the same question. In many other exercises on Duo, just savoir + infinitive is used to mean "to know HOW to [verb].