If the expired invention patents in the United States are replaced, the performance will definitely improve. Can I apply again in China? I also want to apply for a patent for invention.

You can do this. Most inventions find technical problems in the existing technology, make corresponding improvements, solve corresponding technical problems and apply for patents.

Whether you can get authorization, the most important thing is whether the technical scheme of the invention is novel, creative and practical. Simply put, it is to see whether the improved content (that is, the invention point) can solve the corresponding technical problems and whether it can be realized. If it meets the requirements, it's all right.

In addition, it is not necessarily foreign, it can be domestic, it can also be effective, and it is not necessarily an expired patent. As long as it is noted that the improvements made in valid patents may be authorized, but they may not necessarily be implemented. You should pay attention to this.

I hope I can help you!