fall into a decline meaning in English

衰弱, 生肺病

After his wife ' s death , he fell into a decline
他在妻子死一蹶不振
She fell into a decline and died soon
她得了肺病，不久便死了。
They are storing food for the cold season when everything falls into a decline
刚一入夏，蚂蚁就开始储备冬天的食物。
Follow the slump of the nasdaq , it seems the appealing of the capital venture falling into a decline
美国是风险投资的发源地，其历史可追溯到20世纪的20 ? 30年代。