介词、副词填空

--Thank you very much _____ helping to repair my computer.

--That's all right. Thanks _____ your letter, I can come in time and repair it for you.

-Thank you very much ________ helping me to repair my old computer．

-That’s all right．Thanks ________ your letter, I can come in time and repair it for you．

1. A.
   for; for
2. B.
   to; to
3. C.
   to; for
4. D.
   for; to

--Thank you very much ________ helping me to repair my old computer.

--That's all right. Thanks ________ your letter, I can come in time and repair it for you.

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