我唯一的抱怨是缺乏茶点。

My only ___complaint was the lack of refreshments.

关于教学人员，我唯一的抱怨是他们没有留出足够的时间进行个别辅导和必要的帮助。

My only ___complaint about the teaching staff is that they did not allow enough time for individual tuition and help when needed.

持续的延误是乘客们主要的抱怨。

The constant delays are a major ___complaint from passengers.