The truth is that nobody can be positive all the time, and that goes for verbs too. There’s really only one way for any verb to show a negative side, and that’s in the form of what is termed a negative verb. The term is misleading, however, because the verb remains its usually sunny self and simply dons a hostile auxiliary, most typically in the form of not. A child who goes to school on most days, for example, but comes down with strep throat, does not go to school until the doctor says it’s OK to return.
It should be noted that not is most often attached to a form of to have, to be, or to do in the creation of a negative verb. This combination of have + not, is + not, or do + not is the auxiliary to the main verb in the sentence, which does not change. Thus, when discussing a meal in a lavish restaurant, a happy diner might report that the meal tastes wonderful, while a less-delighted diner might complain to the waiter that the food doesn’t taste very good, considering the expense. The first diner, however, doesn’t use the auxiliary in the positive statement by saying that the meal does taste good.
In English, it is possible to use an auxiliary in a positive way. One example is to express agreement with something that has just been stated. If the happy diner’s companion had just said that his or her meal tasted great, one way to agree with it is to say, “Yes, the food does taste good.”
Ironically, the auxiliary can be used outside of the negative verb formation to express disagreement as well. For example, if the happy diner overheard the disgruntled one complaining about the food, he or she might counter the complaint by stating the food does, indeed, taste great. Most of the time, however, English speakers leave off the auxiliary for simple, positive statements.
In the past, the present, or the future, the only job the negative verb must perform is to turn a statement on its head. A busy CEO will snarl at a subordinate, “We haven’t got time for this nonsense,” and it doesn’t necessarily literally mean the time has run out but that the CEO’s outlook is negative. A child who wants to stay in the pool will kick up a fuss when it’s time to leave by proclaiming, “I’m not leaving!” The child’s exasperated parent might respond, “I don’t want to hear it.” In all cases, the meaning of the negative verb unit is clear.