我们找不到合适的替代品，所以只能用旧零件代替。

We couldn't find proper ___replacements, so we had to use the old parts instead.

教练决定让替补队员上场替换受伤的主力球员。

The coach decided to make ___replacements for the injured starting players.

我们需要订购一些备用零件作为替换件。

We need to order some spare parts as ___replacements.