Question

when to use a/an/the/zero article ​

Answer 1

a + singular noun beginning with a consonant: a boy; a car; a bike; a zoo; a dog

an + singular noun beginning with a vowel: an elephant; an egg; an apple; an orphan

a + singular noun beginning with a consonant sound: a user (sounds like 'yoo-zer,' i.e. begins with a consonant 'y' sound, so 'a' is used); a university; a unicycle

an + nouns starting with silent "h": an hour

a + nouns starting with a pronounced "h": a horse

In some cases where "h" is pronounced, such as "historical," you can use an. However, a is more commonly used and preferred.

The can be used with noncount nouns, or the article can be omitted entirely.

"I love to sail over the water" (some specific body of water) or "I love to sail over water" (any water).

"He spilled the milk all over the floor" (some specific milk, perhaps the milk you bought earlier that day) or
"He spilled milk all over the floor" (any milk).

Do not use THE before:

1)names of most countries/territories: Italy, Mexico, Bolivia; however, the Netherlands, the Dominican Republic, the Philippines, the United States
2)names of cities, towns, or states: Seoul, Manitoba, Miami
3)names of streets: Washington Blvd., Main St.
4)names of lakes and bays: Lake Titicaca, Lake Erie except with a group of lakes like the Great Lakes
5)names of mountains: Mount Everest, Mount Fuji except with ranges of mountains like the Andes or the Rockies or unusual names like the Matterhorn
6)names of continents (Asia, Europe)
7)names of islands (Easter Island, Maui, Key West) except with island chains like the Aleutians, the Hebrides, or the Canary Islands

Do use THE before:

1)names of rivers, oceans and seas: the Nile, the Pacific
2)points on the globe: the Equator, the North Pole
3)geographical areas: the Middle East, the West
4)deserts, forests, gulfs, and peninsulas: the Sahara, the Persian Gulf, the Black Forest, the Iberian Peninsula


    In English grammar, the term zero article refers to an occasion in speech or writing where a noun or noun phrase is not preceded by an article (a, an, or the).
      In general, no article is used with proper nouns, mass nouns where the reference is indefinite, or plural count nouns where the reference is indefinite. Also, no article is generally used when referring to means of transport (by plane) or common expressions of time and place (at midnight, in jail). In addition, linguists have found that in regional varieties of English known as New Englishes, omitting an article is often done to express non-specificity.