Is the thank-you letter written to the teacher signed?

Of course, you should sign your name, saying that it is appropriate for someone to send you a letter.

Teachers generally have the idea of being close to others. For example, once I sent a holiday greeting to my teacher, without signature, the teachers replied very little and it was official. By contrast, in the case of my signature, it is different.

the meaning of signing someone is just to tell the other party who you are; The signature of a so-and-so respects not only tells the other party who the letter is, but also means to show respect and respect to the other party.

Signature XXX is mostly used among peers, or in short messages sent to younger generations and subordinates, and is not suitable for sending to elders and leaders. The signature from XXX is used to send messages to elders and leaders, but not to peers and younger generations.

If you sign XXX in the short message, it means that you and the recipient are close peers or the other person is your junior, then there is not much respect in the short message, so you can be casual. But if it's from someone, it means it's sent to someone who needs respect, such as a leader, so we should always pay attention to using honorifics in short messages and not be too casual.