The most powerful signal of stress is a change of pitch on the vowel.（）

判断题Of the four possible tune movements, high fall is used for statements and wh-questions; high rise is used for questions asking for repetition of something; low rise is for yes no questions, etc. and fall rise is for corrections and polite contradictions.（）

判断题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.（）