"Leaves" - Reasoning: Leaves contain veins to transport water through the leaf, and as people would need to be up close to see them. Hence, these veins go unseen as they spend most of their time up in trees attached to branches. You only really get to see them when they fall to the ground.
"Wind" - Reasoning: "Eye" sounds like "i", and the fact that the answer "cannot see" hints that this is the case. Wind, especially high wind, can feel biting, and in literature, the wind is often said to bring a "biting cold", or similar. The voice of the wind is depicted as being quiet or loud, depending on how strong the wind is. Loud winds are often associated with keeping people up during the night.
"The Seven Deadly Sins" - Reasoning: Each sentence structure portrays one of the seven deadly sins from Christian theology, with the exception of the final 5 words. In order according to the riddle, these are; gluttony, sloth, wrath, lust, greed, pride and envy. The final 5 words, "whose feet on Earth remain", act in conjunction with the section on envy, demonstrating the perspective of a sinner in hell, who is envious of those still alive, and thus can still repent for their sins in order to enter Heaven.
"Graveyard" or "Cemetery" - Reasoning: Both "people lie" and "people sleep" are indications of many people using this place to lie down, or to sleep, which in itself is an odd thought. Crying and weeping indicate that this is a sad place, and the continued use of "people" allows this to mean not just those who are lying down or sleeping, but those who come to visit them there, (i.e. mourners). People come to ask the person grave why they did what they did that resulted in their death, as a form of mourning, or to ask their chosen God or Gods why they took that person to their grave. And peoples solitude refers to people sleeping on their own, or the mourners usually coming the mourn privately.
"A Clock" - Reasoning: Seeing the time on a clock can bring you relief, (e.g. your work shift nearly being over), a curse, (e.g. how long you still have left of a work shift), or simple clarification of what time it is. A clock is always running but always returns to where it began, to repeat. Thus, it is stuck in a loop. And as punching at work, appointments, taking to children to daycare, watching a film at the cinema, et cetera, all require you to be at a place at a certain time, time, which you read on a clock, does rule your life. The only exception is when you do not have a schedule to keep. And traditionally, clocks are usually placed on a wall, above eye level, so many people can look at it to see the time
"The Four Seasons" - Reasoning: This riddle takes the perspective of plant life during these times of the year, where each line represents one of the four seasons of the year; Spring, Summer, Autumn and Winter. Spring - where flowers are blooming - Summer - where fields of farm crop mature and turn golden in colour, before being harvested - Autumn - where the tree's shed their leaves and days grow shorter - and Winter - where the cold leaves frost and freezes plants.