ProblemsIn Problems $19-41,$ use the underlined letters to express the statement symbolically$\mathrm{.}19.$ The $1906$ earthquake obliterated $80\%$ of San Francisco and caused devastating fires. O$^$ D$20.$ Our genetic make$-$up consists of dominant and recessive genes. dv R$21.$ DNA does not usually exist as a single molecule, but instead as a pair of molecules held tightly together. ~$-$SM$22.$ Either you get vaccinated or risk becoming infected. CVF$23.$ The computer prints an error message if the employee's salary is a negative number. N$-7$ E$24.$ Many commuters do not take the Long Island Rail Road intoManhattan$\mathrm{.}7$ C$25.$ Itis not true that asquare is neiterarectanglenor a rhombus$\mathrm{.}26.$ Monument Valley is called the valley of rocks and has been featured in many movies depicting the American West$\mathrm{.}27.$ Economic equilibrium is achieved if and only if the manufacturer's supply is equal to the consumer's demand. A $+$E$28.$ If an albino laboratory rat has red eyes and white fur, it is an iconic model for scientific research$\mathrm{.}29.$ Your body mass index is calculated from your weight and height, and measures average body fat. $($W$^$H$^$B$30.$ Glacial calving will keep occurring if and only if global warming continues at its present pace$\mathrm{.}31.$ An incomplete sentence is called a sentence fragment if and only if it lacks either a subject or a predicate, or does not communicate a complete thought$\mathrm{.}32.$ If an animal is in hibernation, then it is in a state of metabolic depression and it needs to store enough energy to last for the entire winter season.$--$DE$33.$ You may be exempt from federal jury service if you are a member of the armed forces on active duty or a public officer who is actively engaged in full$-$time public duties.