She often works at night对 at night提问

When does she often work?
at night 意思是在晚上，是表示时间的词，因此用when提问。因为没有be动词，就需要加助动词do/does,因为主语是单三，所以加does

when she often works?

When does she often work?
楼上的没加助动词！
特殊疑问句由 特殊疑问词+be动词/情态动词/助动词+问题 构成

When does she often work?
at night 意思是在晚上，是表示时间的词，因此用when提问。还有助动词的问题，同楼上。