Usually low key is used for emphasis and contrast; mid key indicates an expected, neutral attitude; and low key provides low information.（）

判断题Pitch is produced by frequency of vibration of the vocal cords. The higher the frequency, the higher the pitch.（）

判断题Of the two types of sentence stress, sense stress shows contrast, while logical stress shows meaning.（）

判断题The back-chaining technique means the students repeat a sentence after the teacher, starting from the end part of the sentence and moving towards the beginning.（）

判断题A phoneme is the smallest distinctive sound unit, incapable of change in different phonetic environments.（）

判断题Consonants vary depending on where and how the air stream gets through, the place and movement of the tongue, and also whether the voice is used or not.（）