用英文定义blank verse和Free Verse.

【Blank verse】 is poetry written in unrhymed iambic pentameter.[1] It has been described as "probably the most common and influential form that English poetry has taken since the sixteenth century"[2] and Paul Fussell has claimed that "about three-quarters of all English poetry is in blank verse."[3]
The first documented use of blank verse in the English language was by Henry Howard,Earl of Surrey in his translation of the Æneid (c.1554).He was possibly inspired by the Latin original,as classical Latin verse (as well as Greek verse) did not use rhyme; or he may have been inspired by the Italian verse form of Versi Sciolti ,which also contained no rhyme.The play,Arden of Faversham (circa 1590 by an unknown author) is a notable example of end-stopped blank verse.
【Free verse】 is a form of poetry that refrains from consistent meter patterns,rhyme,or any other musical pattern.
Some poets have explained that free verse,despite its freedom,must still display some elements of form.Most free verse,for example,self-evidently continues to observe a convention of the poetic line in some sense,at least in written representations,thus retaining a potential degree of linkage,however nebulous,with more traditional forms.Donald Hall goes as far as to say that "the form of free verse is as binding and as liberating as the form of a rondeau."[1] and T.S.Eliot wrote,"No verse is free for the man who wants to do a good job."[2]
Some poets have considered free verse restrictive in its own way.In 1922 Robert Bridges voiced his reservations in the essay 'Humdrum and Harum-Scarum.' Robert Frost later remarked that writing free verse was like "playing tennis without a net".