Which of the following descriptions about the IP address of the VLAN interface of the H3C Layer 3 switch is correct?

Which of the following descriptions about the IP address of the VLAN interface of the H3C Layer 3 switch is correct?
A . As long as an IP address is configured for a VLAN interface, the switch has a three-layer routing and forwarding function
B . Only when two or more VLAN interfaces are configured with IP addresses can the switch have the function of Layer 3 routing and forwarding
C . When configuring the primary IP address for the VLAN interface, if there is already a primary IP address on the interface, you must delete the original primary IP address to configure a new primary IP address
D . You must delete the secondary IP address before deleting the primary IP address of the VLAN interface

Answer: BD