他总爱挑小毛病，这让我心里很不舒服。

His habit of ___niggling over small things really bothers me.

他总是对别人的衣着吹毛求疵，却从不提建设性意见。

He always ___niggles about people's outfits but never offers constructive advice.

她对餐厅唯一的抱怨就是服务太慢。

Her only ___niggle about the restaurant was the slow service.