由于主唱生病了，他们找了个临时替补来完成演出。

They got a ___fill-in to finish the show because the lead singer was sick.

工人用填充材料修补了地板上的缝隙。

The workers used ___fill-ins to repair the gaps in the floor.

测试卷上的填空题你只需要填写单词。

For the ___fill-ins on the quiz, you only need to write single words.