Why does verb plus ING become a noun?

Gerund knows from its name that it has the functions of verb and noun, so it can be used as subject, predicative, object and attribute in a sentence. Let's give an example of its syntactic function:

(1) Gerund as subject:

A.fishing is a relaxing pastime. Fishing is a relaxing pastime.

Climbing the mountain is very tiring. Mountaineering is very tiring.

B. When some adjectives such as good, boring, stupid, wonderful, useless, difficult, good, etc. Used as a predicative and a gerund as a subject, it can be used as a formal subject. For example:

He watches TV all day long. Watching TV all day is boring.

It is difficult to translate poetry into other languages.

C. However, when some adjectives such as important, essential, impossible, necessary, etc. When used as a predicative, the subject can only be infinitive, not gerund. It's important to stay healthy. Good health is very important.

When nouns such as D.it is+no good/no use/fun are used as predicative, gerund is used later. At this time, it is also the formal subject, and the gerund phrase is the subject. For example:

Sailing in the sea is very interesting. Sailing at sea is very interesting.

E our common placard "No …" is composed of "No+ gerund".

For example:

No parking. No parking. No smoking. No smoking.

(2) Gerund as predicative:

My favorite pastime is playing chess. My biggest hobby is playing chess.

(3) Gerund as the object:

A. As the object of some transitive verbs:

Common verbs are: suggest, avoid, delay, escape, excuse, joy, consider, complete, deny, fantasize, keep and mind.

Postal telephone, forgiveness, exercises, suggestions, imagination, etc. Need, want and require are followed by gerund, which means passive meaning. For example:

Would you mind opening the door? Would you please open the door?

Fancy meeting you here. Fancy meeting you here.

Some verbs such as think, find and consider can be used as formal objects.

For example:

I don't think it's useful to talk to such people.

We find stamp collecting very interesting. We find stamp collecting very interesting.

B. As the object of a preposition:

He left without saying goodbye to us He left without saying goodbye to us

As soon as I arrived at the airport, I saw my mother standing in the crowd and waving to me. As soon as I arrived at the airport, I saw my mother standing in the crowd and waving to me.

C. Be the object of some phrases:

Common phrases include giving up, continuing, postponing, unable to help, unbearable, worthy, committed to, accustomed to, accustomed to, opposing persistence, expecting, worrying, keen, like, good at, tired of, interested in, afraid of, etc. Example:

I am looking forward to spending my summer vacation in Kunming. I am looking forward to spending my summer vacation in Kunming.

He gave up smoking months ago. He gave up smoking a few months ago.

When some phrases are followed by gerunds as objects, the prepositions in the phrases can be omitted. Commonly used phrases are as follows:

He spends a lot of time reading newspapers every day. He spends several hours reading newspapers every day.

We should not waste time arguing. We can't waste time arguing.

The young doctor lacks experience in this kind of operation. The young doctor lacks experience in this kind of operation.