Which subway line should I take, and where do I need to transfer?

Which subway line to take and where to reverse need to be determined based on the specific starting point and end point. For example, if you depart from Beijing and want to go somewhere, you may need to take Line 2 first and then transfer to another line at a certain station. Here’s a hypothetical example:

If you take Beijing Metro Line 2 and want to go to Beijing West Railway Station, you can transfer to Line 4 at Xizhimen Station. Therefore, the answer is: take Line 2, reverse at Xizhimen Station and transfer to Line 4. Please note that specific lines and transfer stations will vary based on actual conditions.