1.turn back 扭轉；掉過頭來

The team were forced to turn back after an avalanche killed seven sherpas who were helping carry equipment.
在雪崩造成搬運設備的7名夏爾巴人死亡以后，探險隊被迫折回。

In trying to turn back the clock the european commission has been guided by a simple demand that banks shrink their balance-sheets, without worrying about how they do it.
歐洲委員會為了扭轉局面，對各個銀行僅有一個簡單的要求，即縮小資產負債表，但銀行具體怎樣做就不在它的關注之列了。

2.thought to 認為

It is thought to be a new species.
它被認為是一個新物種。

Like all mr kim's boys he is thought to have been educated at exclusive international schools in switzerland.
與金正日的其他兒子一樣，金正云據信也曾在瑞士一所貴族國際學校讀書。