I responded with "The mother is ordering many kilograms of tomatoes" and was marked wrong. Am I?
Nope - that answer was simply not in the system yet. Please report it if you ran into it again.
Is 'kilogramo' ever shortened to 'kilo' in Esperanto, like in English and Spanish?
Nur "kilo" estas "keel" en la angla, laŭ la vortaro de lernu.net .