What skills can ordinary people learn once and never forget?

I think it's dialect. I lived with the older generation when I was a child. It is a dialect environment. For the next ten years, I hardly touched it. Some words understand the meaning, but they cannot be translated and repeated accurately. Last year, I accidentally came into contact with dialect-related work for some time. Some difficult words and expressions are carefully remembered and followed like English words, and they make rapid progress within one month. Dictation is written after repeated pauses in slow play for more than five times. Within two weeks, you can reach the level only by listening once in a hurry. A year later, I was no longer in the dialect environment, and I couldn't speak fluently because of my slow communication (stuttering). But it's easy to integrate quickly when you get in touch with it, which is much easier than learning a foreign language. I'm not from other places. I've been in this city. The local situation is that this kind of environment is relatively rare. ) naturally can't speak dialects. More than half of my friends who grew up locally can't, but can only reach the level of a few greetings. Their pronunciation and tone are like babbling. When I was in primary school, the slogan "Speak Mandarin and be a civilized person" was everywhere. Speaking dialects at school should be criticized. Many parents have restrained their accents at home since childhood, and don't speak dialects in front of their children to avoid their children being contaminated with local accents. For those who can't learn, even if they have a strong learning ability and have consolidated 234 foreign languages, they may not be able to integrate into this dialect all their lives if they want to understand it with their heart. Some locals have mastered foreign dialects, but they still can't understand local dialects. My classmate's father is a foreigner and came here to get married and have children. My classmate grew up here and is fluent in dialect. Twenty or thirty years later, his father still doesn't understand the dialect, so he can only cut out a few words and listen to them roughly, just like when we just listened to the provincial dialect next door. Now I deeply feel that it is a pity that those students at home deliberately did not touch dialects when they were children. It's great to play many dialects in Mandarin. However, the dialect level of this generation is not as good as that of the older generation (the dialect of the older generation is better than Mandarin), which can only be equivalent to learning a foreign language well. There is no such environment for the younger generation in the future to contact. Even if young people after 1980s and 1990s can understand it, it is difficult for them to communicate in dialects, and it is also difficult for them to do so after 00. Inheritance is more difficult than learning a strange foreign language, and the more you grow up, the more valuable you feel.