Question

—Hi, Bruce. Here is a letter for you.
—Thanks. I wonder         

1. A.
   who the letter was from
2. B.
   who was from the letter
3. C.
   who was the letter from
4. D.
   who from the letter was

Answer 1

A
英语宾语从句中一般为陈述语序。句意：嗨，布鲁斯，这有你的一封信。——谢谢。我想知道这封信是来自谁的。短语be from来自。结合语境可知疑问词为宾语从句的逻辑宾语，选项BCD结构有误，故选A。
考点：宾语从句