Goal: Change each sentence into direct speech (what the person actually said). Below each answer I explain the steps a teacher would use: identify the type of sentence (statement or question), change pronouns/time words if needed, and adjust verb tense (backshift) only when necessary.

1. Given: Anna explained that ice melts at 0 degrees.
   Direct: Anna explained, "Ice melts at 0 degrees."
   Steps: This is a general truth, so we keep the present simple (no backshift). Omit "that" in direct speech.
2. Given: Philip said that he arrived in Russia in July.
   Direct: Philip said, "I arrived in Russia in July."
   Steps: Change the pronoun "he" to "I" (because Philip speaks about himself). Past simple ("arrived") stays the same.
3. Given: Anna added that Philip likes to travel.
   Direct: Anna added, "Philip likes to travel."
   Steps: This is a habitual fact (present simple), so no backshift. Keep the subject "Philip" as in the original.
4. Given: Suzy knew that Shakespeare was born in 1564 and told her friends about it.
   Direct: Suzy told her friends, "Shakespeare was born in 1564."
   Steps: Turn the reporting into direct speech addressed to her friends. The fact uses past simple passive ("was born"), so it stays.
5. Given: Robert asked when Leo Tolstoy died.
   Direct: Robert asked, "When did Leo Tolstoy die?"
   Steps: This is a reported question. Change to question form with auxiliary "did" (past simple) and use inversion. Add a question mark.
6. Given: The teacher told us that the Romans first came to the British Isles in the first century BC.
   Direct: The teacher told us, "The Romans first came to the British Isles in the first century BC."
   Steps: Historical fact in past simple — keep the past tense. Use "told us" and put the fact in quotes.
7. Given: John said that he had been to Russia three times.
   Direct: John said, "I have been to Russia three times."
   Steps: Reported past perfect ("had been") indicates the original direct speech used present perfect ("have been"). Change pronoun "he" to "I."
8. Given: We all knew that Columbus discovered America in 1492.
   Direct: We all said, "Columbus discovered America in 1492."
   Steps: Historical event in past simple — no tense change required for the fact itself. Use "we all said" to introduce the quoted statement.
9. Given: Anna wanted to know where the Volga originates.
   Direct: Anna asked, "Where does the Volga originate?"
   Steps: This is a reported question about present fact. Change to direct question form with auxiliary "does" (present simple) and inversion. Add a question mark.
10. Given: Boris said that he had never been to the desert.
    Direct: Boris said, "I have never been to the desert."
    Steps: Reported past perfect ("had never been") usually comes from present perfect in direct speech ("have never been"). Change "he" to "I" and restore present perfect.