part of speech – n. a class of words (such as adjectives, adverbs, nouns, verbs, etc.) that are identified by the kinds of ideas they express and the way they work in a sentence

phrase – n. a group of two or more words that express a single idea but do not usually form a complete sentence

modal verb – n. a verb (such as can, could, may and might) that is used with another verb to express possibility, necessity or permission

tense – n. a form of a verb that is used to show when an action happened

polite – adj. having or showing good manners or respect for other people