重點(diǎn)講解：
1. stumble on/upon
意外發(fā)現(xiàn)；偶然看見(jiàn)；
eg. History relates that they stumbled on a magnificent waterfall.
歷史上記載他們?cè)馔獾匕l(fā)現(xiàn)了一處壯觀的瀑布tYrugpUJ4w3gW*QIU2。
eg. I stumble upon the rare book in a second-hand bookstore.
我在一家舊書店偶然找到這本珍貴的書*r;eA#oYlP#NkN。
2. by chance
偶然；碰巧；
eg. He picked up a purse on his way there by chance.
他碰巧在去那兒的路上撿了一個(gè)錢包l&ASm-3vwx=9E!UQk[T。
eg. Life gets better not by chance, but by change.
生活變得美好，不是偶然，而是我們努力改變的結(jié)果Gq9@gE]PV];GMS%2。
3. sit back
不插手；袖手旁觀；
eg. They didn't have to do anything except sit back and enjoy life.
他們只需置身事外，享受生活*O&MId4lrHt00%@=!4。
eg. They showed me that there are real, wonderful people being treated unjustly and that I cannot sit back and let that happen.
他們讓我真實(shí)的看到這樣一群善良的人受到不平等的對(duì)待，而我不能坐視不理--A]J-b1(IF2G。