除了…都；几乎；差不多
Merriam-Webster Online Dictionary
all but (adverb)very nearly - almost would be all but impossible
Merriam-Webster Online Thesaurus
all but (adverb)very close to but not completely
SYNONYMS:
about, all but, borderline, fair, fairly, feckly, more or less, most, much, near, nearly, next to, nigh, practically, somewhere, virtually, well-nighRELATED WORDS:
appreciably, by and large, chiefly, largely, mainly, mostly; kind of, partially, partly, somewhatNEAR ANTONYMS:
absolutely, altogether, completely, entirely, fully, plain, plumb [], quite, thoroughly; totally, utterly, well, wholly; barely, hardly, scarcely