Can you tell us where we can buy this kind of dictionary?(同义句转换）

Can you tell us where we can buy this kind of dictionary?(同义句转换）
Our teacher seemed to have changed a lot in the last two years(同义句转换）
_____ _____ _____ our teacher have changed a lot in the last two years.
失去的时间一去不复返了。
Lost time won't return_____ _____.