10. The system of claim 9 , where the one or more computers, when determining the at least one refining instruction, are to identify grammatical features from the second set of one or more tokens.
9. A system, comprising: one or more computers to: receive a first string related to a natural-language voice user entry and a second string including at least one natural-language refinement to the user entry, the first string and the second string being a pair of successive user entry strings; parse the first string into a first set of one or more tokens and the second string into a second set of one or more tokens; determine at least one refining instruction from the second set of one or more tokens; generate a plurality of candidate refined user entries based on the first string, the second string, and the at least one refining instruction, each of the plurality of candidate refined user entries being generated based on at least a portion of each of the first string and the second string, each of the plurality of candidate refined user entries being different than the first string and the second string; select a refined user entry from the plurality of candidate refined user entries; and output the refined user entry.