when drinking water think of its source; remember where one's happiness comes from; 饮水思源
Every tree has its roots and every river has its source. 木有本,水有源。
cause of a disease; 病源
source of income; 财源
Yuan Qianyao 源乾曜
牛津高阶第八版
美国韦氏词典
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维基百科 (自由的百科全书)