Rules to Remember (about Determiners)
1. A, An, TheA and an are used before countable Singular Nouns. A is used before a word beginning with a consonant sound, while an is used before with a vowel sound ; as,
A pen is to write with.
An elephant is a huge animal.
Our hen laid an egg today.
The is a weakened form of that : The is used to particularise a person or a thing ; as,
Bring me the book lying on the table.
The dish you prepared was very delicious.
2. This, That, These, Those
This, that, these and those point to objects denoted by the Nouns that follow them ; as,
This man is a raw villager.
That horse runs very fast.
These mangoes are very sweet.
Those girls must be rewarded.
This and these point to the objects which are near, while that and those point to the distant objects.