Do you know of a reason why "they tried every means" wasn't accepted? Is it bad English?
«They tried every measures.» ne estas. Ĉu estas ebleco raporti post la ekzerco?
This Esperanto sentence looks unnatural to me, (it really confused me when I first saw it), "Cxiu" literally means "Everybody", not "Everything".
Surely the correlative should be "All (things)", (I can't remember what that is in Esperanto).
Edit: It's "Tuta".
Yes, ĉiu does mean everybody, but it also means every one of this noun here. In this instance the noun is rimedo. If the noun is a specific something (ĉiuj la porkoj manĝis ĉiujn la karotojn, for an instance) the correlative ends in ~u. If the noun is not specific, or specified (Mi ŝatus koni ĉion) then it gets the ~o ending.
-u is an indicator (i.e. which), while -o is a class (i.e. what). You can indicate what you're drinking (tea) or which you're drinking (out of these five teas, which?).
Ho, wait, -u is the suffix for individual things. So "tiu libro" is "that individual book", or just "that book", because English doesn't differentiate those. If a noun is omitted, it becomes "that individual", and "person" is added. So "tiu" without a noun is actually "tiu homo" (that specific person).
In this sentence, we have a noun (rimedo), so the "tiu" refers to that.