Defining adjective clauses are used to describe an unspecified noun. NO commas are needed. Non-defining adjective clasuses are used to provide further information of a specified noun (e.g. proper noun). Commas should be put in front of and at the end of the adjective clause. The adjective clasuse in this case can be omitted while the meaning of the remaining sentence is still clear. 1. Sally Lee said the monster which was on the beach was horrible. (Since we do not know which "monster", so we use the adjective clause "which was on the beach" to decribe it, and no commas are needed. This is a defining adjective clause.) 2. The scientists who studied the Wildman thought that it was a kind of Neanderthal Man. (Similar to 1, we do not know which scientists. Defining adj clause.) 3. The Mantis Prawn, which is very dangerous, can stop the heart in four minutes. ("Mantis Prawn" is a proper noun, so the adj clause "which is very dangerous" is just to provide further information. We still know "Mantis Prawn" if the adj clause is omitted, so it is a non-defining clause. Commas are placed in front of and at the end of the adj clause.) 5. With some species of animals it's the males who get pregnant. (In this case, the adj clause "who get pregnant" is used to complement the meaning of the sentence. Without the adj clause, this sentence is meaningless, so it is a defining adj clause. NO commas are needed.) 6. The Dodo, whose appearance looked loke a huge chicken, lived on earth hundreds of years ago. (Similar to 4, "Dodo" is a proper noun. Non-defining adj clause.) 7. The boy who saw Yeti lived on a mountain in Nepal. (Similar to 1, we do not know which boy we are talking about, so the adj clause "who saw Yeti" help us know which boy we are describing. Defining adj clause.) |