grease characteristic

例句：

1. 1. The old engine needs more grease to run smoothly.
   这台旧引擎需要更多油脂才能顺畅运行。
2. 2.The car's engine is running fine without any grease.
   这辆汽车的引擎在没有油脂的情况下运行得很好。
3. 3. To keep the machine running smoothly, it's important to regularly grease the gears.
   为了保持机器顺畅运行，定期给齿轮加润滑油是很重要的。