16. The method of claim 12 , the operations further comprising: in response to a user selection of one of the alternative translations, replacing the corresponding segment of the plurality of segments with the selected alternative translation in the presented translation text.
12. A method performed by a system comprising one or more computers, the method comprising: receiving data identifying source language text; receiving a translation for the source language text from a machine translation system, the translation including translated text corresponding to the source language text and segmentation data for the translated text, wherein the segmentation data includes a plurality of possible segmentations of the translated text, the plurality of possible segmentations dividing the translated text into a plurality of segments; receiving one or more alternative translations for each of the plurality of segments from the machine translation system; sending executable instructions that, when executed by a user device, cause the user device to perform operations comprising: displaying a user interface; displaying the source language text and the translated text in the user interface of the user device; presenting, in the user interface, a slider having a plurality of positions, each position of the plurality of positions corresponding to one of the plurality of possible segmentations; arranging the plurality of segmentations in an order from a smallest segmentation to a largest segmentation; and displaying, upon receiving a user input via the slider, a switching between the plurality of possible segmentations, wherein for each one of the plurality of possible segmentations that are displayed during the switching, the corresponding alternative translations for that possible segmentation are also displayed, wherein moving the slider from a first toward a second opposed position of the plurality of positions displays the switching starting with the smallest segmentation and progressing toward the largest segmentation.