判断题 Syllables are short when they are stressed.（）

判断题 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.（）