precursor
n. （事物）先驱，先兆；（尤指经新陈代谢形成另一种物质的）前体，前质
例句
He said that the deal should not be seen as a precursor to a merger.
他说这次交易不应该被看作是合并的前兆。
《柯林斯英汉双解大词典》
Error is often the precursor of what is correct.
错误常常是正确的先导。
《新英汉大辞典》
We talked about the artificial hip, which is a modern precursor of the splint I talked about before.
我们说到的人造髋关节就是我之前讲过的夹板的现代前身。
