The axle doesn't work smoothly. It needs oiling.

轮轴发涩，该上油了。

The lift didn't work smoothly.

这电梯运转得不顺畅。

The machine is at work smoothly.

机器正在平稳地运转。

Under his guidance, we finished the work smoothly.

在他的指导下，我们顺利地完成了工作。

Under this guidance, we finished the work smoothly.

在他的指导下，我们顺利地完成了工作。