Use 'a' with nouns starting with a consonant (letters that are not vowels),
'an' with nouns starting with a vowel (a,e,i,o,u)
NOTE:
An before an h mute - an hour, an honour.
A before u and eu when they sound like 'you': a european, a university, a unit
The indefinite article is used:
Notice also that we usually say a hundred, a thousand, a million.
NOTE: that we use 'one' to add emphasis or to contrast with other numbers:
I don't know one person who likes eating elephant meat.
We've got six computers but only one printer.
Articles in English are invariable. That is, they do not change according to the gender or number of the noun they refer to, e.g. the boy, the woman, the children
'The' is used:
1. to refer to something which has already been mentioned.
An elephant and a mouse fell in love.
The mouse loved the elephant's long trunk,
and the elephant loved the mouse's tiny nose.
2. when both the speaker and listener know what is being talked about, even if it has not been mentioned before.
'Where's the bathroom?'
'It's on the first floor.'
3. in sentences or clauses where we define or identify a particular person or object:
The man who wrote this book is famous.
'Which car did you scratch?' 'The red one.
My house is the one with a blue door.'
4. to refer to objects we regard as unique:
the sun, the moon, the world
5. before superlatives and ordinal numbers: (see Adjectives)
the highest building, the first page, the last chapter.
6. with adjectives, to refer to a whole group of people:
the Japanese (List of nationalities in English), the old
7. with names of geographical areas and oceans:
the Caribbean, the Sahara, the Atlantic
8. with decades, or groups of years:
she grew up in the seventies
Determiners are words placed in front of a noun to make it clear what the noun refers to.
The word people by itself is a general reference to some group of human beings. If someone says these people, we know which group they are talking about, and if they say a lot of peoplewe know how big the group is.
These and a lot of are determiners in these sentences.
There are several classes of determiners:
Definite and Indefinite articles
the, a, an
Demonstratives
this, that, these, those
Possessives
my, your, his, her, its, our, their
Quantifiers
a few, a little, much, many, a lot of, most, some, any, enough, etc.
Numbers
one, ten, thirty, etc.
Distributives
all, both, half, either, neither, each, every
Difference words
other, another
Question words
Which, what, whose
Defining words
which, whose
The following words are pre-determiners. They go before determiners, such as articles: such and what, half, rather, quite
Adverbs of time tell us when an action happened, but also for how long, and how often.
When adverbs are usually placed at the end of the sentence:
This is a neutral position, but some when adverbs can be put in other positions to give a different emphasis
Compare:
"For how long" adverbs are usually placed at the end of the sentence:
Notice: 'for' is always followed by an expression of duration:
'since' is always followed by an expression of a point in time:
"How often" adverbs expressing the frequency of an action are usually placed before the main verb but after auxiliary verbs (such as be, have, may, must):
Some other "how often" adverbs express the exact number of times an action happens and are usually placed at the end of the sentence:
When a frequency adverb is placed at the end of a sentence it is much stronger.
Compare:
Adverbs that can be used in these two positions:
'Yet' and 'still'
Yet is used in questions and in negative sentences, and is placed at the end of the sentenceor after not.
Still expresses continuity; it is used in positive sentences and questions, and is placed before the main verb and after auxiliary verbs (such as be, have, might, will)
If you need to use more than one adverb of time at the end of a sentence, use them in this order:
1: 'how long'2: 'how often'3: 'when' (think of 'low')