用“介词+关系代词”引导的定语从句改写下列句子（2道）
We visited Beijing University last week where I spent four happy happy years.
We visited Beijing University last week _____ _____ I spent four happy years.
The bamboo grows best at the place where there is enough rain and water.
The bamboo grows best at the place ____ _____ there is enough rain and water.