In the early stages of the language, the infinitive was a full inflected form. In Old English, it had the ending –an with one inflected form, the dative –enne, which under the influence of –an became –anne. This form was used after the preposition to, denoting indirect object mainly. Due to the erosion of inflections throughout Middle English, it became identical in form with the present and the imperative. So in modern English, the infinitive is not considered as a separate form of the verb, but as one of the uses of the base form.
USES OF THE BARE INFINITIVE
MODAL VERBS, DARE, NEED
WITH DO
HAD BETTER, HAD BEST, HAD RATHER, HAD SOONER, RATHER THAN
WITH SOME VERBS: LET, MAKE, HELP, SEE, HEAR, WATCH, NOTICE,
USES OF THE TO INFINITIVE
BE, HAVE, OUGHT, USED, BE ABLE
PURPOSE
KNOw FORGET LEARN TEACH + How
ACCUSATIVE CONSTRUCTION: COMMAND, ORDER, REqUEST, INVITE, ADVISE, TELL, ASK…
ADJUNCT OF ADJECTIVES AND NOUNS sorry to hear, offer to help
GERUND
FORM
USES
AS NOUN
Plural doings ´s walking´s sake
Possessives his leaving
Articles a warning
Coordination with substantives walking and a good diet
AS VERB
Adverbials
Objects
Subject he´s got a sense of it being her duty
Perfect, passive
AFTER PREPOSITIONS
AFTER CERTAIN VERBSa
advise,
allow, try,
attempt,
be afraid
Begin,
can´t bear
continue,
go on,
hate,
intend,
like,
love,
mean,
permit,
prefer,
propose,
recommend,
regret,
remember
start,
INFINITIVE AND GERUND
Remember, forget
Try
Begin, start, continue
Hate, like
Stop
Allow permit advise recommend (if object: to inf)