onset

疾病的早期症状在发病初期就出现了。

The early symptoms appeared at the ___onset of the disease.

在疾病的早期阶段就进行治疗非常重要。

Treatment at the ___onset of the disease is very important.

流感症状的初期通常会伴随高烧和乏力。

Fever and fatigue usually mark the ___onset of flu symptoms.