飞机平稳着陆。

The plane made a ___smooth landing.

两次政治管理之间的过渡异常平稳。

The transition between the two political administrations was remarkably ___smooth.

尽管谈判复杂，合并过程进展顺利，没有发生任何事件。

Despite the complex negotiations, the merger process proceeded ___smooth and without incident.