Why some words must be followed by infinitives and some words must be followed by gerunds

In English, some transitive verbs are followed by the infinitive as an object, and the infinitive often indicates a future action, such as: kitty plans to take linda out(Katie is going to take Linda out).

Also commonly used is: expect to do. refuse to do.

plan to do. decide to do. agree to do.

Lean to do learn to do. hope to do. prepare to do.

want to do. wait to do. choose to do.

wish to do wish to do.

After the verb, add the gerund doing as the object v +doing sth

complete consider delay deny detest endure enjoy escape prevent fancy finish finish imagine mind miss postpone postpone postactise recall resent resist resume continue risk adventure.

Most of them are fixed usages and need to be memorized.

The infinitive of the verb followed by the preposition is generally to add the leakage of the conjunction, and the special infinitive is constructed, such as: he gives me some advice on how to learn english

The infinitive is marked, and to is concatenated with a verb; There is no one who has a numerical conjugation, and the verb characteristic it has; The subject-object definite form complement, but the predicate is not allowed; not plus infinitive, negation structure to keep in mind; Question words and indefinite sharp file bad style, forming a phrase that is meaningful; Careful scrutiny and more thinking, accurate judgment has a basis.

Analysis: "to + verb form" is its basic constituent form, that is, the mark of the infinitive. It has no conjugation of the verb and number, regardless of whether the subject is any pronoun, singular or plural, the infinitive has no inflections.

But it still retains the characteristics of a verb and can have its own object or adverbial.

For example: manage to do sth, do sth to do, wisth to do sth, apply a to b, seem to see, see to investigate, etc.

1、let's assume for the sake of argument that we manage to build a satisfactory database.For the sake of discussion, it may be assumed that we have succeeded in establishing a satisfactory database.

2、in such circumstances we can't afford to wait any longer.Circumstances do not allow us to wait any longer.

Infinitives, e.g. want, help, need, like, let, make

There are many verbs that need to be followed by infinitives, such as want (to do), and they cannot be listed one by one.

There is no one that directly follows the verb form, but there are better ones that follow the verb, such as stop (doing), keep(doing), ......

Generally speaking, verbs like let make are directly followed by the original form of the verb, while words like tell ask advise are added after the infinitive form, like help can be added infinitive, or the original form can be added, I hope it can help you.