high-rate sand filters for swimming pools work on a vacuum principle much like an ordinary vacuum cleaner. the filter draws in water instead of air (this is why air in the filter system or lines in unwanted - air will cause the "vacuum" pressure to fall). submerged and suspended particles are drawn in from the bottom drains while surface floating debris is drawn in through the skimmer assembly.

which statement would be the best final sentence in a conclusion on the topic of sand filter maintenance?
a) the pump will cause water to flow from the pool through the hair and lint pot.
b) set the pump on backwash whenever it needs to be cleaned with the cleaning process.
c) the multiport valve on the pump controls the flow of water depending on the setting.
d) over time the sand bed will become plugged with dirt and require a cleaning process known as backwashing.

Which choice most effectively combines the sentences at the underlined portion

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

Choose a theme addressed by the writers you have studied in this unit, such as coming of age, the conflict between greed and morality, the horrors of war, the injustice of racism, the excesses of materialism, or the divide between rich and poor. explain the relevance of this theme in today’s world and how it affects you. provide examples to support your position.