A、  B、  C、  A所给出的问题询问信件是否已经寄出。因此以“sent”作为回答的选项(A)显然是正确答案。注意提问中的letter与选项(C)中的little发音上有些相似，不要混淆。

Do you think you could plug in the projector for me?
(A)Sure, Where’s an outlet?
(B)You can turn it off now.
(C)I’ll finish the project by six.

Did you send the letter to Ms. Bixler already?
(A)I sent it yesterday.
(B)I haven’t read them yet.
(C)She wanted only a little.