Articles:

in the sea.
2) a/an, the: singular countable nouns refer to

a group of people, animals, things.
A dog is a domestic animal. (all dogs)
The tiger is a wild animal. (all tigers)
3) a/an = “per”(one)
She goes to the theatre three times a/per month.

(the Odeon); hotels (the Ritz); restaurants (the Terrace); museums/galleries (the

Tate Gallery); newspapers (the Times); rivers/seas/oceans (the Black Sea); mountain rages (the Alps); groups of islands (the Japanese); deserts (the Gobi desert); musical instruments (the guitar); families (the Smiths);people (the President); historical events (the Second World War).

holidays, colours, drinks, meals and languages.
I love tennis.
3) Countries,

cities, streets, parks, islands, continents, lakes.
4) pubs, restaurants, shops, banks, hotels.
5) Purpose for which they exist: bed, church, college, court, hospital, prison.

Continuous (was/were + V-ing)

Past Perfect (had + v3/-ed)

Past Perfect Continuous

(had been + V-ing)