a two-hundred-word letter
a letter of two hundred words
都可以
two-hundred-word 是形容词,作定语修饰letter,意为”两百字的”
英语中表所属时,若名词为有生命的,则直接加”`s”,如Peter`s book(彼得的书”;若名词为无生命的,则用连接,如the window of the world(世界之窗)
two hundred 表示”两百”,是复数,所以word 要加s
a two-hundred-word letter or a two hundred words' letter
是, a latter with 200 word.或
a two-hundred-word letter
word 不可数
a letter of 200 words
a two-hundred-word letter