School is an example like you have a load of work and its hard and u keep going cuz u know it will get you someone good adn another is running a marothon even though its hard you just keep going. hope this helps and please rate below :)
Vertebrata
Vertebrata is a group that contains various organisms which possess vertebrae (backbones). Animals that belong to the group are called vertebrates, and they include mammals, birds, fish, amphibians, and reptiles. The backbones in the animals extends from the head to the tail, and it encloses and protects the main nerve cord. The body of vertebrates is divided into trunk, and tail regions. They also possess a unique tube shaped brain, a distinct head, and three pairs of sense organs.
They use mud to build their home so it is also for protection.
Perihelion marks the begging of summer when the earth is closest to the sun.