  We study the effect of query order on computational power, and show that
$\pjk$-the languages computable via a polynomial-time machine given one query
to the jth level of the boolean hierarchy followed by one query to the kth
level of the boolean hierarchy-equals $\redttnp{j+2k-1}$ if j is even and k is
odd, and equals $\redttnp{j+2k}$ otherwise. Thus, unless the polynomial
hierarchy collapses, it holds that for each $1\leq j \leq k$: $\pjk = \pkj \iff
(j=k) \lor (j{is even} \land k=j+1)$. We extend our analysis to apply to more
general query classes.
