Course paper on theoretical grammar

2.2. Grammatical analysis of verb .
Lexical verbs are normal verbs like run, play and jump, while auxiliary verbs are those that add extra meaning to lexical verbs like was running, have run and did run. In analysis, lexical and auxiliary verbs are distinguished from each other according to four properties known by the acronym NICE: negation, inversion, code and emphasis. Each of these concepts is discussed in turn.
Mowarin identifies four ways that negation can be achieved in English through affixation e.g. unnecessary; through inclusion in a noun phrase e.g. I have no friends; lexically e.g. I refused the offer; and at the sentence level through the use of the word not or its contraction as part of the verb phrase e.g. I do not like fighting or I don’t like fighting.
According to Huddleston it is the last of these that primarily distinguishes auxiliary verbs from lexical verbs - the word not and its contraction are only used with auxiliary verbs. Inversion is another distinguishing feature between lexical and auxiliary verbs that was discussed in Section 2.4. Only auxiliary verbs are capable of inverting with the subject to
Form a question . For example, the auxiliary is inverts in the following
sentences not eat: Lucy is eating and Is Lucy eating?