60岁学滑雪绝非易事！

Learning to ski at 60 ___is ___no ___mean ___feat!

说服整个委员会绝非易事。

Convincing the entire committee ___is ___no ___mean ___feat.

在短短三个月内组织如此大型的会议绝非易事。

Organizing such a large conference in just three months would ___be ___no ___mean ___feat.