Why do researchers think today's teens are less happy than teens in earlier generation?

Match each excerpt to the correct stanza structure. 1. it was many and many a year ago, in a kingdom by the sea, that a maiden there lived whom you may know by the name of annabel lee; and this maiden she lived with no other thought than to love and be loved by me. (from "annabel lee" by edgar allan poe) 2. o thou, new-year, delaying long, delayest the sorrow in my blood, that longs to burst a frozen bud and flood a fresher throat with song. (from "in memoriam" by alfred lord tennyson) 3. nature’s first green is gold, her hardest hue to hold. her early leaf’s a flower but only so an hour. then leaf subsides to leaf. so eden sank to grief,; so dawn goes down to day. nothing gold can stay. (from "nothing gold can stay" by robert frost) 4. at sestos hero dwelt; hero the fair, whom young apollo courted for her hair, and offered as a dower his burning throne, where she should sit for men to gaze upon. the outside of her garments were of lawn, the lining purple silk, with gilt stars drawn; (from "hero and leander" by christopher marlowe) quatrain couplet octave sestet