The reason why I used a semicolon in the sentence in the OP was because I was once taught by my language adviser. She was an editor and author. Well, I'm not saying that everyone needs to listen to my late English language adviser; I just want to explain why I used it.
She told me when you write two sentences and if these two sentences are interconnected (the second sentence explains the first) and you can use a semicolon.
I respect her like I respect all of you here. teechar has been helping me with my English writing in the Editing Forum since 2019, and jutfrank, you're the only one who commented on my spoken English and gave me valuable advice on my spoken English and written English. I think both of you are correct. So, the best way to solve this problem is to write down two sentences, one with the semicolon and the other with a period.
Again, I appreciate your help. In China, especially mainland China, it's not easy to learn idiomatic English. Teachers of English here are talking sh*t. Textbooks of English teach nonsense. It's sadly true that children don't learn English at schools but in language schools because they can learn natural English. We buy books online from the UK and the US. We learn from native speakers but it's very expensive and we can't always find a good teacher.
I'm very lucky for having all of you here as my teachers. Much appreciated. I remember the other day when I was praised by a professional who teaches Translation and Interpretation in a university here I was very happy because after a decade-long devotion to this language, I am finally recognized by my peers. Some native speakers on WR who once listened to my voice messages (like the voice mail) told me they'd been to many countries and taught in those countries and my spoken English is good. I think my spoken English is passable. But each time when others said that my spoken English is good, I replied to them "because I have a group of wonderful teachers online".
And you are one of those wonderful teachers.