In your first weeks of English you met a pair of openers for saying that something exists: one shape for a single thing, another shape for several. The rule is easy to state and easy to drill. Then you watch a film, and within ten minutes a character uses the singular shape in front of an obviously plural noun, and nobody in the room reacts. If you have quietly wondered whether your textbook lied to you, it did not. It left something out.
The rule is real, and it is the one to learn
Here is what your course teaches, in its two shapes.
There is a problem with the booking.
There are two problems with the booking.
The verb agrees with the noun that follows it, exactly as verbs agree everywhere else in the language. Nothing about this construction is special in careful writing, and the second line above is the shape you want whenever you mean more than one thing. That is worth saying plainly before anything else, because the rest of this page is about the moments when your ears will tell you otherwise, and about the one place further down where the rule itself bends.
One point of English grammar is worth making before the examples multiply. The word that opens both example sentences above is not really doing its ordinary job. Elsewhere in the English language it is an adverb that refers to a specific place; here it refers to nothing at all. It is a placeholder that fills the subject slot so the sentence can begin, while the real subject waits behind the verb. The whole construction exists in order to say that something exists, and it holds the thing back until after the verb. That is why the verb takes its grammatical number from what follows rather than from what precedes it: the noun behind it is the thing being announced, and the opening word means nothing on its own.
What you are actually hearing
In speech, the singular opener turns up in front of plural nouns constantly, in every major variety of English, from every kind of speaker. It is not regional, it is not carelessness, and it is not a sign of poor education. Listen for it in the next thing you watch and you will catch it within a few minutes.
There’s two buses an hour.
There’s a lot of people waiting outside.
Notice what both lines above have in common: the verb is contracted onto the word in front of it. That is the whole explanation. Once it is shortened and attached, speakers stop processing it as a verb at all. It becomes a single fixed chunk whose job is to announce that something is about to be mentioned, and a chunk does not agree with anything. The full, unshortened singular form in front of a plural noun is much rarer, because there the verb is still audible as a verb and speakers feel the clash. The plural form can be contracted too, but the result is awkward to say and almost never written, which leaves the singular chunk covering both jobs.
It reaches informal writing as well, wherever people write the way they talk: messages, comments, captions, anything typed quickly. What you will not often find is the same chunk in edited prose, because an editor generally takes it out. Usage guides have objected to it for well over a century without denting it at all, which tells you how firmly it sits in the spoken language.
Recognise it; do not produce it
So the honest answer splits in two. As a listener, treat it as a fact about spoken English: when it goes past you, nothing has gone wrong, you have not misheard, and your grammar is not out of date. Nobody explains this in a beginner classroom, which is exactly why it unsettles the learners who are otherwise doing well.
Your own output is a different matter. Editors correct it, teachers mark it, and examiners count it under grammatical accuracy in both writing and speaking. Copying it buys you nothing: the plural form costs you one extra syllable and nothing else. And there is an unfairness you should simply plan around: a form that passes unnoticed from a fluent speaker is read as an error when it comes from a learner. That is unfair, and it is also how it works.
A quick test, then, before you send anything that matters. Imagine the sentence read aloud by a newsreader rather than by a friend. If the newsreader version is the one you want, use the full plural form. Producing it correctly is free: formal writing has no tolerance for the spoken chunk, and no reader has ever complained that the longer form was too long.
The case your textbook skipped
One situation is genuinely different, and no beginner course mentions it: a list.
There is a knife and two forks in the drawer.
There are two forks and a knife in the drawer.
Both lines above are normal, and the only difference between them is which item comes first. When a list follows the opener, the verb agrees with the item nearest to it rather than with the total, so a single first item pulls the singular verb even though the drawer holds three things. Reverse the order, as in the second line, and the verb turns plural. This is not a spoken shortcut and not a modern slip; careful writers have done it for centuries. Your course leaves it out because it complicates a rule that beginners need to install first.
Questions and negatives: the grammar does not change
Most ESL courses install the two positive shapes in the first term and never come back to them. Learners who have drilled those shapes then lose the distinction the moment the sentence stops being a plain statement. It should not happen, because forming a question or a negative changes the word order, not the agreement.
Is there a problem with the booking?
Are there two problems with the booking?
There is not a problem with the booking.
There are not any problems with the booking.
In the first two lines above the verb simply hops in front of the opening word. Everything else stays where it was, and the noun still decides which form of the verb you need. In the last two the negative attaches to the verb instead, and again you look past it to the noun to know which form to use. One extra habit is visible in the final line: after a plural negative, English usually prefers the non-specific determiner to a bare number word. That small choice is worth copying, because getting it right is most of what makes a negative sound native.
Singular or plural: which noun the verb is listening to
Agreeing with the following noun is easy advice to give when the noun is a plain countable one. It stops being easy when the noun belongs to a type your first course never sorted out.
There is a lot of traffic on the ring road.
There are three chairs in the waiting room.
There is a team of engineers on site.
There are six children in the group.
The first line above contains an uncountable noun. Nouns of that type have no plural form and cannot be counted one by one, so you use the singular verb with them however much of the stuff you are describing. The second line is the plain countable case, behaving exactly as your course promised. The third holds a collective noun, a single word naming a group of people; British English allows either verb with these, depending on whether you mean the group acting as one body or its members acting separately, but after this particular opener the singular is far more common and it is the safer choice in an exam.
The fourth line is the one that catches people out. Its noun is plural, but it does not end in the letter that normally marks a plural, so learners read it as singular and reach for the wrong verb. Irregular plurals do this constantly, and they are common enough in everyday speech that you cannot route around them. If that group of nouns still slows you down, the reference page on plural forms that refuse to follow the rule is where to fix it.
Quantity phrases that hide the real noun
Easily the most common source of error at intermediate level is a quantity phrase sitting between the opener and the noun. The phrase looks like the subject, so learners agree the verb with it, and the sentence comes out wrong.
There are a lot of people waiting outside.
There is a lot of noise in the corridor.
There are plenty of seats left.
There is plenty of room left.
The quantity phrase is identical across the first pair of lines above, and identical again across the second pair. What changes each time is the noun at the end of it, and that noun is what the verb answers to. If you can count the thing, use the plural verb; if you can only measure it, use the singular. The phrase in the middle never decides, however long it grows, and a phrase of four or five words is exactly where a careful learner loses track.
Past, future and perfect: the same choice in other tenses
Nothing about this pattern is locked to the present. Move the verb into another tense and the construction carries over unchanged, still taking its number from the noun that follows it. Only the conjugation of the verb changes.
There was a mistake in the invoice.
There were three mistakes in the invoice.
There will be a meeting on Thursday.
There have been complaints about the noise.
The first two lines above move the choice into the past, where it works exactly as it does in the present: one form for a single thing, another for many. The third line is the easy case. Once a modal joins in, the main verb has only one form left, so the singular and plural question disappears and a single shape covers both. The fourth line brings the choice back: in the perfect it is the auxiliary in front that changes with the noun, even though the participle behind it never does.
Confused words: three spellings, one sound
One further confusion is worth clearing up, because it costs marks in writing rather than in speaking. The word that opens every example on this page has two homophones: a possessive determiner, and a pronoun with a contracted verb attached. All three sound identical when spoken, and a spellchecker will not help you, because each of them is a real English word in its own right. They are among the most confused words in the language, and the other two words have nothing to do with existence at all.
There are two boxes by the door.
Their boxes are by the door.
They’re leaving the boxes by the door.
Only the first line above is the existence construction under discussion here. The second opens with a possessive determiner and tells you whose the boxes are; the third opens with a pronoun and a contracted verb and tells you what somebody is doing. Learners rarely confuse the three meanings. They confuse the three spellings, under time pressure, in an exam, and the mark is lost anyway. If that trio is a habitual slip of yours, the reference page on words that trap even native writers is the drill that clears it.
What to do this week
Install the agreement rule properly for your own use. The lesson on saying that something exists lays out both shapes with their question and negative forms, and the practice set that makes you choose between one thing and many is worth ten minutes a day until the choice stops costing you any thought. If it is the verb itself that slows you down rather than the choice, keep the reference page for the three present forms of the language’s most important verb open beside you. Mastering the choice is a fortnight of short sessions, not a term of study.
Then stop grading what you hear against what you write. Understanding and producing are separate skills at every stage, and they are allowed to disagree; the page that sorts everything here by level is built on exactly that assumption.