1. Cost of resource maintenance and update: Subject Network needs to continuously invest manpower and material resources to maintain and update academic resources on the platform to ensure the accuracy and timeliness of resources.

2. Acquisition cost of special resources: The subject network provides some special academic resources, such as exclusive or paid resources.

3. Service and support costs: Subject Network provides some value-added services and technical support, such as academic paper writing guidance, academic conference information, academic exchange platform, etc.