主唱生病了，他们找了个临时替补来参加今晚的演出。

The lead singer was ill, so they got a ___fill-in for tonight's performance.

我们用沙子作为混凝土之间的填充物。

We used sand as a ___fill-in between the concrete blocks.

请填写表格上缺失的联系方式。

Please ___fill in the missing contact information on the form.