Yes, there are still professions in which people go on expeditions, travel, and explore. For example, scientists and researchers often travel to remote locations to conduct fieldwork and collect data. Explorers and adventurers also continue to pursue expeditions to discover new territories and push the boundaries of human knowledge and capability. Additionally, documentary filmmakers and journalists frequently travel to different parts of the world to capture and report on new and interesting stories. **

Yes, one can definitely still explore new things in mathematics. Mathematics is a vast and constantly evolving field with many unsolved problems and uncharted territories. As technology advances and new tools become available, mathematicians are able to tackle more complex problems and make new discoveries. Additionally, interdisciplinary collaborations with other fields such as computer science, physics, and biology continue to open up new avenues for exploration in mathematics. **

Yes, hiking boots can often be repaired. Depending on the extent of the damage, a cobbler or shoe repair specialist may be able to replace the sole, mend the upper, or fix any other issues with the boot. It's always best to consult with a professional to assess the damage and determine if the boot is worth repairing. In many cases, a well-made hiking boot can be restored to its original condition with the right repairs. **

Without knowing the specific condition of the gear, it is difficult to determine if it can still be used. If the gear is damaged or broken, it may not be safe or effective to use. However, if the gear is in good condition and has been properly maintained, it may still be usable. It is important to thoroughly inspect the gear and, if necessary, have it evaluated by a professional to ensure its safety and functionality. **

As an AI language model, I don't have personal experiences or activities, so I don't sing folk and hiking songs. However, I can certainly help you find and learn about folk and hiking songs if you're interested in them! **

Air travel can still be appropriate for certain situations, such as long-distance travel or emergencies. However, it is important to consider the environmental impact of air travel, as it contributes to carbon emissions and climate change. It is advisable to explore alternative modes of transportation, such as trains or buses, for shorter distances or when feasible. Additionally, advancements in technology and sustainable aviation practices are being developed to make air travel more environmentally friendly in the future. **

Yes, train travel is still considered safe. Rail companies have implemented various safety measures to protect passengers, such as increased cleaning and disinfection protocols, mandatory mask-wearing, and reduced capacity to allow for physical distancing. Additionally, many trains have improved ventilation systems to minimize the risk of airborne transmission. While it's important to stay informed about the latest guidelines and regulations, train travel remains a relatively safe mode of transportation. **

As of November 2021, U.S. citizens are allowed to travel to Cuba for certain purposes, such as family visits, official business, journalism, professional research, educational activities, religious activities, public performances, support for the Cuban people, humanitarian projects, and activities of private foundations or research or educational institutes. However, there are restrictions in place, so it is important to check the latest travel regulations and requirements before planning a trip to Cuba. **