7. In robotic applications, springs are often used to mimic the _ and _ of human muscles. This requires springs with _ properties, which can be achieved through the use of _ or ___ materials. (Options: elasticity, flexibility, variable stiffness, shape-memory alloys, elastomers) 8. Springs that are exposed to _ environments, such as those used in _ or _, benefit from _ treatments to prevent ___ and maintain their mechanical properties. (Options: corrosive, marine, chemical processing, protective, rusting, degradation)