The common wording of the punctuation rule “always put a dash in front of“ this ”is both true and false. The fact is that in this version the rule covers only a part of the cases of using this word. It is understood that the dash in front of this word is always, without exception, necessary if it is a connection between the subject and the predicate, in other cases other algorithms and rules may apply.
Dash in original designs
As you know, one of the main situations when you need to put a dash, are sentences, the basis of which is expressed by a noun, numeral or infinitive, in them a sign is placed between the subject and the predicate:
Jigsaw is a tool that even a woman can easily master. (The sign is placed between the subject and the predicate, expressed by nouns.)
Late spring is a time of love, hope and expectation.
School is a time for self-determination and personality formation.
Dash in the same bundle designs
Often, unsuccessful formulations of elementary school methodologists provoke mistakes in sentences where the predicate is accompanied by a bunch. Everywhere, primary schoolchildren are explained that "a dash is put in place of (!) The word" this "." Such a formulation works as a tool for setting characters in sentences without a bunch, but it is misleading if you need to put a character in a sentence with this bunch. The fact is that from the thus formulated “clue” it logically follows that if the dash is put “instead of” the word, then when it is in the sentence, the sign is no longer necessary. Many students have a persistent stereotype that leads to persistent mistakes: a dash is not put in sentences with a bunch.
Meanwhile, punctuation rules are strictly opposite. In the case when the predicate has a bunch, a dash before it is mandatory. Examples:
Autumn is a time for creativity and debriefing.
To love is to sacrifice oneself.
Adopting a child is not a gift to him, but first of all to himself.
Coming always on time is respect not only for others, but above all for yourself and your business.
Dash before predicate with denial
A dash before the word “this”, if it is a connection between the subject and the predicate, is necessary even in those cases when there is no need for a sign without the connection.
So, a dash is not set when the predicate contains a negation:
Little lop-eared puppy is not a toy. (The sign is not placed, since the predicate, the pronounced noun, is the negative particle "not.")
Even the most talented movie is not a substitute for a book.
Making a controversial diagnosis for a seriously ill patient is not the domain of the nurse.
In the case when the predicate with negation is accompanied by a bunch, before “it” is always a dash:
A little lop-eared puppy is not a toy. (The sign is placed because the “not” particle follows the link.)
Even the most talented movie is not a substitute for a book.
Making a controversial diagnosis for a seriously ill patient is not the domain of the nurse.
Dash in front of a predicate, pronounced infinitive
In constructions with infinitive predicates, this sign is placed regardless of whether the link is used or not.
Re-reading a book that I read in childhood is like finding yourself in childhood. Re-reading a book that I read in childhood is like finding yourself in childhood.
To truly love a person is how to start living anew.
Swim in the lake in the early morning - how to get younger.
Sitting at the same table with old friends is like stopping the passage of time.
Generalizing word
The second case, which presupposes the obligatory setting of the mark, is the use of a generalizing mark. A dash is always set in front of him in these cases.
Go fishing, swim in the river, pick berries, cook at the stake - these are all favorite signs of the village summer.
Seagulls, lamb clouds, sandpipers of sandpipers, tender water of the lake - all this attracts and is long remembered.
Scandals, clarification of relationships, small deceptions - is this not a way to break the relationship?
Particle
The confusion with the universal wording “a dash is always put before this” arises from the fact that a word that formally looks always the same can actually be different parts of speech. In the case when it comes to a particle, a dash before “this” is not set:
How did they leave without waiting for the fireworks?
Well, where did you all go together?
So it was he who then called and warned that the roads were slippery.
Indication word on the border of parts of a complex sentence
In many cases, one of the parts of a complex sentence begins with the index word, the meaning of which is to explain, explain or supplement the previous part, and also draw a conclusion from it. In such cases, intuitively, many place a dash in front of “this” instead of a comma. Such a sign is allowed, but it should be borne in mind that the dash changes the intonation of the whole sentence and puts other logical accents. A comma or a dash in front of “it” is certainly needed, but the choice of the character in general remains with the writer. In neutral sentences of this type, a comma is placed at the border of the parts of the sentences.
Suddenly a huge bird flew onto the terrace - it was she who had been rustling all night on the roof and did not let her sleep. (The sign on the border of the parts of the sentence conveys the meaning: “So, who didn’t let you sleep!”, “Ah, it turns out, who was rustling!”)
At the very end of the eighteenth century, Pushkin was born; he will change the Russian language and the fate of Russian literature. (The “neutral” sign at the junction of the parts of a complex sentence shows the meaning: "As you know, it was he who changed the Russian language.")
She had a dachshund on her lap; last year we all took her from Voronezh together.
In the garden they grew Manchurian walnut, this is a tree whose fruits are very similar to walnuts.
After comparative turnover
There is no reason for the dash in front of the demonstrative pronoun in intonationally neutral constructions. For example, the question of a sign may arise when a pronoun follows a comparative turnover. In these cases, a comma is always put. If in such a sentence a dash is placed before the word “this”, this is a mistake.
Like any other animal, this creature is able to get used to the person.
Like all other generations, it needs something new and its own.
As if a neighbor silent and agreeing with everything, this tree lives all its life near our house and shakes its branches as a sign of its participation in our life.
However, from such cases it is necessary to distinguish sentences, the basis of which is expressed by a noun, numeral or infinitive and which are complicated by a comparative turnover. In such sentences, after a comparative turn and before the bunch, a comma and a dash are placed:
The scream of a heron flying low over a swamp, like a cry of loneliness or a voice from another world, is always an unpleasant sensation, even for an experienced hunter. (A dash is set as if there was no comparative turn: “The scream of a heron flying low over a swamp is an unpleasant sensation even for an experienced hunter . ” A comma closes the comparative turn.)
New poems by an unfamiliar talented author, like a new opening world, are like confirmation that everything is in order with the world. (A sentence without comparative turnover obviously requires a sign between the subject and the predicate.)
After the Communion turnover or the solitary Communion
In addition, the mark is mistakenly placed after the participle or sacrament turnover. There are no logical reasons for such a sign, apparently, the writer is in the grip of the same stereotype, transferred from special cases to all the others: “a dash is put before“ this ”.”
Forming gradually, this decision grew stronger and stronger, and finally it was made.
Unreachable, this journey so absorbed his thoughts that he could not think of anything else.
Having run up through the meadow, this herd of children released into the wild did not hear and did not see anything but the sun, strawberries and butterflies.
As in the case described above, one should distinguish from such a construction a sentence with a bunch in front of a predicate, a pronounced noun, numeral or infinitive and complicated corporeal turnover. In such sentences, two signs are placed in front of the bundle following a solitary geremonial or turnover:
Leaving forever, mentally looking back at past years, is a true test. (A dash is set for the same reason that it is necessary in the sentence “ Leave forever - a true test . ” The comma in front of the dash is needed as a closing one in the participial turnover.)
Watching children who learn to live by playing and quarreling with each other and copying the behavior of their parents is not only a pleasure and interesting activity, but also an occasion to reflect on themselves. If you reduce the sentence, excluding the subordinate and participial turnover from its structure, then the logic of the appearance of the dash is obvious: “ Watching children is not only a pleasure and an interesting lesson, but also an occasion to think about yourself .” The comma before this sign closes the participle turnover, and in case of its exclusion - the subordinate clause.
So, whether a dash is placed before “this,” if it is not a matter of copyright, almost entirely depends on what part of the speech and on what syntactic role the word is in question.