An antecedent is a word for which a pronoun stands. The pronoun must agree with its antecedent in number. Rule: A singular pronoun must replace a singular noun; a plural pronoun must replace a plural noun. Here are nine pronoun-antecedent agreement rules.
Best Answer: Wrong answer. Well trough is right. But peak is totally wrong. The crest is the highest point on a wave, while the trough, or valley between two waves ...
(If you don't see the sound clips, please try a different browser.) 1  The top wave represents a typical sound wave vibrating at a certain amplitude (its height) and frequency (how many peaks and troughs there are in a certain amount of time).