根据句意，用恰当的单词填空。

1. They were young, then. Now they are             .

2. My hair was short then.  But now my hair is              .       

3. She was fat then.  Now she is              .     

4. I was short in the photo. But now I am               .

试述双侧上尿路结石的手术治疗原则。