Regarding the import-route command, which of the following statements are correct?

In the topology shown in the figure, the following configurations are performed on RTA, RTB, RTC and RTD respectively:
RTA-LoopBack0] ip address 1.1.1.1 255.255.255.255
RTA]ospf 1
RTA-ospf-1]area 1
RTA-ospf-1-area-0.0.0.1]network 10.0.0.0 0.0.0.255
RTA-ospf-1]import-route direct
RTB-LoopBack0] ip address 2.2.2.2 255.255.255.255
RTB]ospf 1
RTB-ospf-1]area 1
RTB-ospf-1-area-0.0.0.1]network 10.0.0.0 0.0.0.255
RTB-ospf-1-area-0.0.0.1]area 0
RTB-ospf-1-area-0.0.0.0]network 20.0.0.0 0.0.0.255
RTB-ospf-1]import-route direct
RTC-LoopBack0] ip address 3.3.3.3 255.255.255.255
RTC]ospf 1
RTC-ospf-1]area 0
RTC-ospf-1-area-0.0.0.0]network 20.0.0.0 0.0.0.255
RTC-ospf-1-area-0.0.0.0]area 2
RTC-ospf-1-area-0.0.0.2]stub no-summarRTC-ospf-1-area-0.0.0.2]network 30.0.0.0 0.0.0.255
RTC-ospf-1-area-0.0.0.2]network 3.3.3.3 0.0.0.0
RTD-LoopBack0] ip address 4.4.4.4 255.255.255.255
RTD]ospf 1
RTD-ospf-1]area 2
RTD-ospf-1-area-0.0.0.2]network 4.4.4.4 0.0.0.0
RTD-ospf-1-area-0.0.0.2]network 30.0.0.0 0.0.0.255
RTD-ospf-1-area-0.0.0.2]stub
Which of the following routes cannot exist in the RTD routing table ______.

Regarding the Stub area and NSSA area of the OSPF protocol, the following statements are incorrect: _______

As shown in the figure, in the IS-IS network, the RTA configuration commands are as follows, please complete them.
RTA]isis
RTA-isis-1]______
RTA-isis-1]interface serial 2/0
RTA-Serial2/0]isis enable 1

In the IS-IS network as shown in the figure, the RTA, RTB, and RTC configurations are as follows:
RTA]isis
RTA-isis-1]is-level level-1
RTA-isis-1]network-entit01.1111.1111.1111.00
RTA-isis-1]interface serial 2/0
RTA-Serial2/0]isis enable 1
RTB]isis
RTB-isis-1]is-level level-1
RTB-isis-1]network-entit01.2222.2222.2222.00
RTB-isis-1]interface serial 1/0
RTB-Serial1/0]isis enable 1
RTB-Serial1/0]interface Ethernet 0/0
RTB-Ethernet0/0]isis enable 1
RTC]isis
RTC-isis-1]is-level level-1
RTC-isis-1]network-entit01.3333.3333.3333.00
RTC-isis-1]interface Ethernet 0/0
RTC-Ethernet0/0]isis enable 1
RTC-Ethernet0/0]interface Ethernet 0/1
RTC-Ethernet0/1]isis enable 1
After the routes of each router are stable, the cost of IS-IS route 192.168.3.0/24 on RTA is ______.