Cách sử dụng
The expression "gain in" is usually used when we want to talk about how much progress or improvement we have made in a certain field or activity. It means to make progress or improve in something. For example, if you have been practicing playing a musical instrument every day for a month and you can now play a new song, you can say that you have gained in your musical skills. This expression is commonly used in academic or professional contexts, but it can also be used in everyday life.