Would you check my sentences?

Hello, native English speakers,

Would you please check my sentences?

1 Tom taught me how to play the guitar.
2 There are some buildings built by my uncle.3
3 I don't know what Nancy wants.
4 When the phone rang, I was watching TV.
5 Come back by eleven thirty.
6 If it rains tomorrow, I won't go there.
7 When I visited Tom last week, he looked well.
8 Stay here until eight thirty.
9a I often played soccer when I was a high school student.
9b I would often play soccer when I was a high school student.
9c I often used to play soccer when I was a high school student.
10 I arrived at the airport much earlier than usual.
11 Who is the youngest in your family?
12 You have to come to school by eight twenty tomorrow.
13 Would you teach me how to solve this problem?

Thanks in advance.

Hirashin

2 seems a little odd, can you put it into context? I'm just not sure how this would be used in actual conversation, not that the sentence seems technically wrong.

The rest look fine to me.

Thanks, Woko.
Then how about this? Is it odd, too ?
The building built by my uncle is huge.

hirashin said:

Thanks, Woko.
Then how about this? Is it odd, too ?
The building built by my uncle is huge.

Click to expand...

Sounds fine to me.

Thanks, Wonko.

1 Tom taught me how to play the guitar. [You could just write "Tom taught me to play guitar."]
2 There are some buildings built by my uncle. [If the buildings are in sight,you could say "My uncle built those buildings." If you're not seeing the buildings at the moment, but are referring to them, you could say "My uncle built some buildings."
3 I don't know what Nancy wants. [Good, best to keep beginner sentences simple and short.]
4 When the phone rang, I was watching TV. ["I was watching TV when the phone rang." makes more sense.]
5 Come back by eleven thirty.[Good]
6 If it rains tomorrow, I won't go there.[You could leave off "there".]
7 When I visited Tom last week, he looked well.[Good, good.]
8 Stay here until eight thirty.[Good!]
9a I often played soccer when I was a high school student.[Good.]
9b I would often play soccer when I was a high school student.[Good.]
9c I often used to play soccer when I was a high school student.[Good, although you're more likely to hear them say "I used to play soccer a lot when I was in high school."]
10 I arrived at the airport much earlier than usual.[Good!]
11 Who is the youngest in your family?[Good]
12 You have to come to school by eight twenty tomorrow.["You need to be at school by 8:20" or "Arrive at school by 8:20" are also good sentences.]
13 Would you teach me how to solve this problem?[Great!]
Excellent! Message me if you want to talk one-on-one about English or learn some slang.

Thank you for the detailed comments, emilyismixed. I appreciate your help. I hope you continue to help me. (Should I say "continue helping" instead?)
Hirashin