... counter and then forgot it 15 An Abyssinian cat and a Himalayan cat (are, is) pictured on a single United States stamp 188 C O M M O N U S AG E E R RO R S Lesson 23 Problems with Modifiers Nouns and ... and 13) and adverbs (Lessons 12 and 13)—how they function, how they differ, and how some adverbs are formed from adjectives In this lesson, we touch on a couple of usage concerns Adjectives and ... (have) written Forms of have and of be and are often used as helping verbs: has left, were chosen, agree PROBLEMS WITH VERBS 179 EXERCISE In each sentence, underline the correct form of the verb...