In addition, scores of check-points are also approved to be useful to improve the ranking of MT systems as additional features at sentence level and document level.
for instance, BLEU fails to sufficiently capture the vitality of natural languages: all grams of a sentence are treated equally ignoring their linguistic significance; only consecutive grams are considered ignoring the skipped grams of certain linguistic relations; candidate translation gets acknowledged only if it uses exactly the same lexicon as the reference ignoring the variation in lexical choice.