顾客向服务台投诉了送货延迟的问题。

The customer ___complained to the service desk about the delayed delivery.

老人向医生诉说他的膝盖总是疼。

The old man ___complained to the doctor about his constant knee pain.

他经常抱怨天气，但从不采取任何措施适应。

He often ___complains about the weather but never takes any steps to adapt.

乘客们向航空公司投诉了航班延误的问题。

The passengers ___complained to the airline about the flight delay.