• An adjectival clause performs the function of a single adjective
• An adjectival clause is usually introduced by: who, where, when, why, which, that
• The adjectival clause is of two types, restrictive and non-restrictive

Restrictive Adjectival Clause

• This is not set off by a comma as it is attached to its substantive, and by so doing, is essential to the meaning of the sentence. For example:
  • Any student who fails the test on the board will be asked to pack and go
  • Any electorate who votes for Mr. Koke is naïve
  • We have told dad the time when the certificate will be available

Non-restrictive Adjectival Clause

• This, on the other hand, describes but does not limit the identity of its antecedent
• It is often set off by a comma as it is usually parenthetical to the main clause, which is to say that if the non-restrictive clause is omitted in a sentence, the sentence will remain without the loss of essential meaning. For example:
  • The woman, who is wearing a blue dress, is my sister
  • The car, which I told you about yesterday, is now on sale
  • Jack Dickson, who supervised the study, has left the country

• NOTE: ‘who’ is used when the answer to the question is the subject of the sentence while ‘whom’ is used when the answer to the question os the object of the sentence. For example:
  • Who is coming with me to the pool?
  • Whom should I rely on this matter?
  • Who likes burger?
  • Whom do you doubt?