a an "and" the?

hy2007

\"The cat is under the sofa\" implies that we all know which particular cat
is being discussed -- perhaps it's already been mentioned recently, or
perhaps it's the family pet.

\"A cat is under the sofa\" means that an unspecified cat is under the sofa.

Hopefully that clarifies the difference between \"the\" and \"a\".

\"A\" and \"an\" mean exactly the same thing as each other, but \"an\" is used
before a vowel sound, and \"a\" before a consonant sound. For example:

  a tree
  an elephant
  a drum
  an MRSA outbreak
  an hour
  a UK citizen

Plurals: the plural form of \"the\" is \"the\". The plural form of \"a\" is
\"some\", though it's optional.

  Singular: I bought the banana from the shop.
  Plural:  I bought the bananas from the shop.

  Singular: I bought a banana from the shop.
  Plural:  I bought some bananas from the shop.
  Plural:  I bought bananas from the shop.