Study the exceptions with plural and singular nouns.
These things are always plural in English:
Scissors
Glasses
Trousers
Jeans
Shorts
Tights
Pyjamas
Glasses
Trousers
Jeans
Shorts
Tights
Pyjamas
Do you like jeans?

Do you wear glasses?

But you can say a pair of trousers/pyjamas/etc. Some plural do not end with -s.
Remember these nouns.
| Singular | Plural |
| Man | Men |
| Woman | Women |
| Child | Children |
| Foot | Feet |
| Tooth | Teeth |
| Mouse | Mice |
| Sheep | Sheep |
| Fish | Fish |
| Goose | Geese |
| Deer | Deer |
| Ox | Oxen |
| Person | People |
| Crisis | Crises |
| Basis | Bases |
| Analysis | Analyses |
| Phenomenon | Phenomena |
| Formula | Formulae |
People - plural
Police - plural

1. The police are here.
2. People are very calm and friendly there.