1. at night 的意思是 during any night，通常表泛指。如：
I often work at night. 我经常在夜间工作。
2. in the night的意思是 during one particular night，通常表特指。如：
The storm blew over in the night. 风暴在夜里停止了。
3. in和during在这里都可以表一段时间内，可互用如：
Everything was quiet during the night. 昨夜万籁俱寂
因此你这道题可以填during或者in
