Here are the sentences converted into reported speech:

50. **Is your sister good at English?" I said to Hoa.**
   - I asked Hoa if her sister was good at English.

51. **Could you cook this fish for me?" My mother said.**
   - My mother asked if I could cook that fish for her.

52. **Don't you know how to behave in lessons?" The teacher told his students.**
   - The teacher asked his students if they didn’t know how to behave in lessons.

53. **Helen said to herself, "Am I doing the right thing?"**
   - Helen wondered if she was doing the right thing.

54. **Yen asked me, "Is the Statue of Liberty in New York?"**
   - Yen asked me if the Statue of Liberty was in New York.

55. **I asked her, "Do you enjoy your English class?"**
   - I asked her if she enjoyed her English class.

56. **I asked my new classmate, "Do you visit the Taj Mahal in India?"**
   - I asked my new classmate if they had visited the Taj Mahal in India.

57. **"Can you go to the concert with me tonight?" our friend asked us.**
   - Our friend asked us if we could go to the concert with them that night.

58. **She said to me, "Are you hungry?"**
   - She asked me if I was hungry.

59. **The man said to her, "Can you play the guitar?"**
   - The man asked her if she could play the guitar.

60. **Thu's mother said to her, "Are you willing to help your friends now?"**
   - Thu’s mother asked her if she was willing to help her friends then.