Exercise: to answer - to reply. Is it right?

I've done this exercise today; is it right?

Complete with "to answer" or "to reply":

1. I must REPLY to his letters today.
2. We must REPLY to your question.
3. Tom must still REPLY to my letter.
4. Margaret must REPLY to me soon.
5. Lucy must REPLY to their question.
6. They must REPLY to our letters.
7. Mary cannot ANSWER you now, because she is in bed.
8. I don't know how to REPLY to your question, I'm very sorry.
9. (If)Tom doesn't ANSWER you soon, he isn't very well.
10. I can't REPLY to your letter, I have no time.
11. We can't ANSWER her because she doesn't understand Italian.
12. They can't ANSWER you because they don't know that language.

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Just a couple of issues, but the actual words that you asked about, REPLY and ANSWER are right. Great work.