此外，主动词是那些具有各种含义的动词，有时后面跟不定式，与to连用。” Ought “是一个半情态动词，因为它在某些方面像情态动词，在某些方面它像一个主动词。不像情态动词，” ought “后面跟to， ” not “后面不能跟to， ” I not ought to go there “是主动词。这在语法上是不正确的。因此，将应当纳入主动词范畴是不合适的。
“Used”完全符合作动词的要求。它有不同的含义。有时，to后面可以跟不定式，例如“I used to go there”。它也用于不定式和分词形式，如used to和used to。这个词也可以出现在“not”、“I didn’t use it”之后。此外，这个词不能用在问题的开头。
英国硕士论文字数分配 ： The differences between the three categories inclusive of main verbs, auxiliary verbs and modals, are not very apparent as there are certain words which may show features of more than one of these categories. The aim in this short essay lies in analysing the properties of “ought” and “used” with regard to these three categories. The scope lies in seeing whether there are any respects in which the use of these terms is different from all the categories or whether it is difficult to decide which of the categories these terms may reside in. The essay is aimed at illustrating personal opinion on which category is best suited for both the terms.
Also, main verbs are those that have all kinds of implications and at times are followed by infinitives in conjunction with “to”. “Ought” is a semi modal verb as it is in certain ways like a modal verb, in a certain ways it acts like a main verb. Unlike modal verbs, for example, “ought is followed by “to” and as main verb it cannot be used after “not”, for example, “I not ought to go there”. This is grammatically incorrect. Therefore, fitting ought into main verb category will not be appropriate.
“Used” completely fulfils the requirements to be a main verb. It has different kinds of meaning. At times, it can be followed by “to” as an infinitive, for example “I used to go there”. It was also be used in infinitive and participle forms such as using to and used to. The term can also appear after “not”, “I did not use it”. Furthermore, the term cannot be used in the beginning of the question.
As per the investigation done in this essay, “Used” and “ought” can be categorized into either of the three categories but not all. For “ought”, modal and auxiliary verbs category suits best. It is evident from the various examples discussed in this essay. Also, “used” can be appropriately categorized as a main verb. It can also be categorized as an auxiliary verb or helping verb. Even though the categories have differences that are not quite apparent but for these two verbs, categorization was possible.