This "stem" originates from the sentence: "There are only 20 actors in Britain", which is usually used to ridicule the repeated use of actors in British movies and TV dramas. The origin of this stem is not very clear, but it has become a popular joke and ridicule. In fact, there are many excellent actors in Britain, but for some reasons, they appear frequently in different movies and TV dramas, which may lead to some fatigue of the audience. This stem also reflects some problems in the film and television industry, such as the lack of diversity and innovation.