he wrote ____ letter to his parents yeaterday.he wrote ____ letter to his p

题目

he wrote ____ letter to his parents yeaterday.he wrote ____ letter to his p
a.a 800words
b.an 800-word
c.an 800-word's
d.a 800-word
顺便说明为什么.

答案

d.a 800-word
a letter 中间加800-word 做修饰定语