1. Articles: There are three articles in English—a, an and the. A and an are called indefinite article.The is the definite article. An article is placed before a noun. If there is an adjective before a noun, the article is placed before the adjective:

2. A/an: Singular count nouns take the indefinite article a/an with them:

Uncount nouns do not generally take an article with them. we do not generally say

3. We use a with singular count nouns beginning with a consonant sound:

Note: That the words university, union, and one begin with a vowel but no a vowel sound. University and union begin with the yoo sound while one begins with the w sound.
Well-known words which begin with a vowel but take a with them are:

4. An: An is used before words beginning with a vowel sound:

The letter h in honest and honourable is not sounded. Common words in English which begin with an unsounded h are:

5. In abbreviations, if consonants begin with a vowel sound, they take an before them:

But if consonants begin with a consonant sound, they take a before them:

6. Note the use of a in the following phrases:

7. The definite Article the: The, the definite article, is a weakended form of that. It is pronounced as (di:) when it preceded a vowel sound and as do before a consonant sound. In meaning also, it is weaker than that. Instead of pointing out, it defines, particularises or singles out:

Prepositions

Prepositions of Time

A number of prepositions may be used to denote time: from Monday; after my return; during the night; till tomorrow; before the bell rings; a quarter to ten. In most cases, it is easy to decide which preposition to use. The following prepositions, however, need special attention.

1. At, on, in

2. By

3. For

4. Since

5. From

6. At, in

7. On, upon

8. Above, over

9. Below, under

10. Into

11. For

12. Against

13. From

14. Out of