飞机平稳的降落归功于飞行员精湛的技术。

The aircraft's ___smooth landing was a credit to the pilot's skill.

得益于新的悬挂系统，这辆车在高速公路上行驶异常平稳。

Thanks to the new suspension, the car's ride over the motorway was remarkably ___smooth.

他文章中两个观点之间的过渡天衣无缝、流畅自然。

The transition between the two ideas in his essay was seamless and ___smooth.