重點講解：
1. be able to do sth.
能做到某事；
eg. You'll be able to read in peace.
你就能安心地讀書了。
eg. It would be nice to be able to afford to retire earlier.
無后顧之憂而能提早退休當(dāng)是件幸事。
2. a variety of
各式各樣；多種多樣；
eg. The island offers such a wide variety of scenery and wildlife.
這個島嶼擁有豐富多樣的景致及種類繁多的野生動植物。
eg. People change their mind for a variety of reasons.
人們會由于種種原因改變主意。
3. track down
追蹤到；追查到；搜尋到；
eg. She had spent years trying to track down her parents.
她已經(jīng)花了好多年時間試圖追尋父母的下落。
eg. I don't know where that old story came from, I've never been able to track it down.
我不知道這則舊傳聞的出處，我從來沒能考證出結(jié)果。