Why
would Elie say "Water was the worst
poison for him, but what else could I do for
him? With or without water, it would be
over soon anyway...'

Eliezer states that water is the worst poison for a person in his father's condition, suggesting that the water is filthy and would further aggravate the situation. He prefers giving his father some soup because it is boiled and offers a healthier option compared to the water they had at the camps.

can you give us the options

shakespeare was famous for writing in iambic pentameter, which is a specific way of rhyming sonnet lines in ten syllables. there are also forms of unrhymed iambic pentameter, as in macbeth, with the noble characters.