onset：the beginning of something, especially something bad

例句：Evidence shows that speaking a second language can help delay the onset of dementia.

onset：开始=beginning，后可接如疾病、经济萧条、战争

例句：Since the onset of the war, the crime rate has skyrocketed.

仿写：Since the onset of the financial crisis，many companies have went broke.

翻译：Since the onset of financial crisis，the investment landscape has changed a lot.

仿写：Since the onset of the war，many children have lost their parents.