thirty-six feet per second up. Very smooth, very quiet ride."

VOA: special.2009.07.15

Like I said, it's very smooth, very polite.

就像我说的，这种说法非常礼貌与流畅。

Why don't 课堂 - SpeakingMax英语口语达人

From 1983 to the present as you just said, the economy has a long period of smooth, robust expansion interrupted by two very mild recessions.

第二时期是从1983年至今，正如你所说，经济长时间处于,平稳强健的发展状态,而只出现了两次轻度衰退。

斯坦福公开课 - 经济学课程节选

It is very fine and smooth.

VOA: special.2009.09.09

The "Why don't" pattern is a very polite, very smooth way to suggest something.

Why don't”句型是一种非常礼貌、流畅地提出建议的方式。

Why don't 课堂 - SpeakingMax英语口语达人