We know that no matter what children say or do before they speak, they will take actions, such as changing diapers and drinking milk. We will interact with children with words and actions. In such a perceptual situation, the development of children's language will also be subtle. He can perceive what kind of person and language he is facing, but it has no effect on his speech.
Of course, children can be exposed to a large number of language types. No matter which side interacts frequently with children in English or Chinese, I believe that children talk to the one who has more communication first. Children have the desire to express themselves, and the desire to speak is also to interact with him. When a child speaks, it must have nothing to do with the language environment, but with a person raised by himself. If children want to switch freely between Chinese and English, they also need a lot of input.
It is common to greet people you know and go out with Chinese speakers, so children will naturally think of Chinese, and when they go out with English speakers, children will naturally think of English, which is why in many variety shows, children of stars often speak both Chinese and English. It is not difficult for young children to speak, but they rarely understand what others mean. This is the same as monolingual environment. Children must understand the meaning while learning a language.