1, gathering+cooking: gathering skills can help players get food and resources, while cooking skills can turn these resources into more nutritious food and improve players' viability.
2. Construction+mechanical engineering: Construction skills can help players build shelters and other facilities, and mechanical engineering skills can help players make tools and equipment and improve production capacity.
3, medical+chemistry: medical skills can help players treat injuries, while chemical skills can help players make drugs and antidotes, and improve players' viability.