i can't understand the letter_____in english.a.writtenb.writec.writingd.have been written请详细说明理由不懂哎,能不能详细点,

i can't understand the letter_____in english.
a.written
b.write
c.writing
d.have been written
请详细说明理由
不懂哎,能不能详细点,

选A write 作letter 的定语.因为letter是被写的,所以write要用过去分词.

a 过去分词做letter的后置定语

a.written letter是被写 用被动语态