Thickening is the usual first step in sludge disposal processing.
污泥處置過程中,濃縮通常是第一道工序。
The first step in protein synthesis is transcription.
蛋白質合成的第一步是轉錄。
It is the reverse of the propagation step in addition polymerization.
這一過程是加聚反應歷程中鏈增長步序的逆過程。
?? 牛津釋義
step in
intervene (to help or hinder sb/sth) 干預(以幫助或阻止某人[某事物]); 介入
If the police had not stepped in when they did there would have been serious violence. 當時若警方遲一些干預就會發生嚴重的暴力事件了.