1.用why是定语从句,就是why后面跟的句子整个修饰reason.
而that是同位语从句,整个句子对reason起到了补充说明的作用.for+名词性短语或者名词
请看The reason why she failed in the exam was that she didn't study hard.that后面是reason的内容.
2..experienced 动词的ed形式一般修饰的是人,此处如果有experiencing就可以选.再考虑experience在这句话中应该理解为经历才对,此时是可数名词前面要加a.quite这个词和very是有区别的,quite意为"相当",修饰形容词时要置于a/an之前.如：it is quite a cold day.这是相当冷的一天.