There are nouns that appear only in the plural form?

Yes, you are absolutely right! There are nouns that appear only in the plural form, even though they refer to a single thing. These are called pluralia tantum (Latin for "plurals only").

Here are some examples:

Objects:

* Scissors

* Trousers

* Pants

* Binoculars

* Pliers

* Glasses (eyeglasses)

* Shorts

Concepts:

* Tidings

* Scabies

* Measles

* Mumps

* Archives

* Contents

Other:

* Police

* Cattle

* People

Why are they only plural?

There are a few reasons why these words are only used in the plural:

* They refer to a single item that has two parts: Scissors, trousers, etc.

* They refer to a collection of things: Contents, police, cattle.

* They are grammatically fixed in the plural: Tidings, measles, mumps.

How to use them in sentences:

* The scissors are on the table.

* He bought a new pair of trousers.

* The police are investigating the crime.

* The good tidings arrived yesterday.

It's important to remember that while these words always appear in the plural form, we do not use a plural verb with them unless they are referring to multiple items. For example, you would say "The police is investigating the crime," not "The police are investigating the crime."