1.a harbinger for sth. 預示著
What of China's past could be a harbinger for its future?
中國過去的哪些經歷能夠預示其未來？

2.over an extended period of time 在相當長的一段時間內
The securities business has developed over an extended period of time, and embodied different features in different countries and periods.
證券市場已經發展了相當長一段時間，而且，不同的國家、不同的時期，其展現出不同的特點也不一樣]fk,gAZgR_Hooc。

3.boots on the ground （派遣到當地去完成某一任務的）人力
"You simply have to have the boots on the ground to manage the fisheries," he said.
他說:“沒辦法，你只能部署人員到當地管理那邊的漁業Dzz@O%)5*nqJBP^。”

4. at the mercy of 在……的掌控之下
Farmers are often at the mercy of the weather.
農民常常要受天氣的擺布G1aFhLkxic-GB8.-HyW。