I said "I would like the knife." It said it was wrong and it should be "a knife." It's the same right?
yes. Report it next time you see it.
Yes, it's the same
how does one know it is 'a 'or "the"?
There is no a or the in Swahili. Use either
"May I have a knife" is a polite way of saying "I ask for a knife" so quite correct.
Surely "I request a knife" is correct??
I request a knife... why wrong?
It's not great English but it's a good translation
Kuuliza also means to ask