Shouldn't "dai" meccanici ... mean FOR the mechanics????? This is so confusing. I wish there was a rule of thumb for all these prepositions. sometimes it's "di" mattina - for "in the morning" ... the next time it's "alla" mattina - for "in the morning'" ... THEN 'Tranne la birra' ... is correct for except for the beer ... WHY NOT USE tranne per la birra ... for except FOR the beer?????
No worries, I vaguely remember having the exact same problem when I first met "chiave". Nouns ending in '-e' are rebellious, they can be male (il ristorante) or female (la notte). I find most of the -e nouns in Duolingo that you learn early are not often used in plural (you don't OFTEN say le notti, although it is correct grammar) so chiave is your first real exposure to "rebellious" nouns.
And just for future reference, both masculine and feminine nouns ending in -e (singular) are -i plural (the restaurants = i ristoranti)
Oh and just wait until you find random exceptions, like "la mano". Don't worry about that yet though ;)
I said "at the mechanics' shop" because it seemed a little incomplete or too informal to just say "at the mechanics,' " and got it wrong. Che peccato! because the translation was simple. There's just this problem of knowing how much or how little duolingo will accept that keeps me on pins and needles! And yes, that English translation above does need an apostrophe to make it correct. I considered saying "I am leaving the key with the mechanics" but was pretty sure that was too far off the range to be acceptable to the program, but one never knows.