CNN news 2010-04-17 加文本

1.because she had actually vanished into an alligator infested swamp area on Friday only to be found yesterday alive and well, it's an incredible story.

only to
only和不定式连用常构成结果状语，表示与预料相反的结果，意思是“竟然……、结果……”。如：

He studied hard only to fail in the exam.

他这么用功，竟然在考场上失利。

He rushed all the way to the station only to miss the train.

他一路冲往车站，结果还是错过了火车。

My wife went home in a hurry only to find the door locked.

我妻子急忙回到家，结果却发现门锁着。

2.Absolutely, you just don't hear stories turning out like this, this way very often...

turn out结果是, 原来是

例句：He said he was a doctor; but later he turned out to be a cheat.
      他自称是个医生, 结果证明他是个骗子。

      The day turned out (to be) a fine day.
      那天倒是好天气。

3. and after four days the odds of finding someone in good health, a relatively good health, or even alive start to fall off very quickly, ...

fall off减少

例句：The number of passengers by this line fell off slightly in January.
      一月份这条航线的乘客数量略有减少。

变坏; 恶化

例句：The cooking fell off remarkably.
      烹饪质量大大降低。