1. Mr. Brown is very delighted. His son has won the first prize in the English speaking contest. (Rewrite the sentence, using RELATIVE CLAUSE) arrow Mr Brown, __

The task is to rewrite the sentence using a relative clause. A relative clause is a type of subordinate clause that modifies a noun by using a relative pronoun such as "who," "which," or "that." In this case, the relative clause will provide additional information about Mr. Brown.<br /><br />The original sentence is: "Mr. Brown is very delighted. His son has won the first prize in the English speaking contest."<br /><br />To rewrite this using a relative clause, we need to combine these two sentences into one, using a relative clause to connect them. The relative clause will describe Mr. Brown's son and his achievement. The appropriate relative pronoun to use here is "who," as it refers to a person (Mr. Brown's son).<br /><br />The rewritten sentence is: "Mr. Brown, whose son has won the first prize in the English speaking contest, is very delighted."<br /><br />Here, "whose" is a possessive relative pronoun used to indicate that the son belongs to Mr. Brown, and it connects the two ideas from the original sentences into one coherent sentence.