By bellyaching I mean inventing poor reasons for not doing what one has been told to do.

我说的牢骚是指捏造牵强的理由，为的是不执行接到的命令。

We expect to hear a lot of bellyaching from traditional book publishers, who already in many cases resent Amazon's power.

我们预计传统图书出版社将有很多抱怨，它们早就对亚马逊的影响力心怀不满。