也许，和风帆一样，它们作为备用品可以在熄灯的时候排上用场。
Perhaps, similar to sails, they make a useful backup for when the lights go out.
太阳帽是许多人夏天防晒的必备用品之一。
幸运的是当时没有备用品所以我的演出取消了。
Luckily there were no spares and I was allowed to skip my performance.
若传动轮粗糙，可换备用品使用并检查压合紧度。
If rough, replace rotating for supplies and check the use of pressure and tight degrees.
若传动轮粗糙，可换备用品使用并检查压合紧度。
If rough, replace rotating for supplies and check the use of pressure and tight degrees.
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