My time in the middle school was one of________ periods of my life.

You can hardly imagine the efforts I have made _____the goal. [ ]

I don’t agree with you two I prefer______ a new car rather than______ it

There are some warnings in some countries ______ overexploitation of underground water has caused the decline of wetland andincrease of desertification.

He __________ his position as president by giving jobs to his friends. [ ]