Reference Designs offer the theory, component selection, and simulation of useful circuits. Circuit modifications that help to meet alternate design goals are also discussed. Comparators are used to differentiate between two different signal levels. Here are some rules to help you add that ending. Language Objectives Spell the - —iA9 form of verbs correctly. Use -ing Words correctly in Sentences. Rule 1: Rule 2: Rule 3: For words that end in a silent (not pronounced) -e, drop the -e and add -ing. Create your own worksheets like this one with Infinite Algebra 1. Free trial available at KutaSoftware.com. Adding and Subtracting Integers Evaluate each expression. 1) 1 - (-4) 3) 5 - 8 5) 2 - (-5) Free trial available at KutaSoftware.com. Create your own worksheets like this one with Infinite Algebra 1. Free trial available at KutaSoftware.com. Adding and Subtracting Expressions with Unlike Denominators You need to determine the Lowest Common Denominator (LCD) (Multiple of the Denominators) Factor the denominators you have to identify what factors of the LCD are missing Multiply the numerator and denominator by the missing factor(s).