出了什么事？/出了什么毛病？（肯定动词，可能的回答如 We missed the train/had an accident<我们误了火车/出了事故>。）
但 who，whose 等后跟 be + 名词或人称代词时，要用疑问动词：
Who are you？
你是谁？
Whose is this？
这是谁的？
What is that noise？
那噪音是怎么回事？
who，whose 等作动词或介词的宾语时，整句当然需要用疑问动词。
You can memorize words in an efficient way if you pronounce them reasonably. Say words correctly, and you will learn them easily. Correct pronunciation means correct spelling of the words. English spelling is not good to guide its pronunciation. But spelling and pronunciation have closed relationship. They match each other perfectly. Sometimes we can pronounce a word according to its spelling. English pronunciation can also guide its spelling. This is a two-way communication.
