1.look back 回顧；倒退

And I look back with pride and amazement.
而當我回顧過去時，心中充滿自豪和驚嘆。

Understanding the tata connection requires a look back at history.
要了解塔塔之間的種種聯系需要回顧一下它的歷史。
2.propel to 推至

Conversely, employees who represent the brand flawlessly and consistently can propel a business to stardom.
反過來,雇員代表和維持品牌可以推動企業不斷輕聲呼喚。

Experts say several factors have helped propel moocs to the center of the education stage, including improved technology and the exploding costs of traditional universities.
專家表示有幾個原因把moocs網教推向了教育舞臺的中央，包括科技的日新月異，還有傳統大學天價的花費。

3.set off 開始；引起

Nichols set off for his remote farmhouse in Connecticut.
尼科爾斯動身去他在康涅狄格州的偏僻農舍了。

The President's envoy set off on another diplomatic trip.
總統的使節開始了又一次外交之旅。

4.focus on 致力于；使聚焦于

That's all you want to focus on.
你只需將你的注意力集中于此。

The project also will focus on key secreted pathogenic proteins.
該項目也將集中于主要分泌性致病蛋白質。