回复：

请教：

"select over"什么意思？

科技英文：

...the compounds with formula I should be selected over compounds with formula II.

 

式I 化合物选自式II化合物吗？还是 式II化合物选自式I化合物？

 

老外是不是说话也常常不严谨？打错介词？

 

谢谢先！

 

>>>>>

 

To select over is to choose in preference to.  

 

This sentence tells you that formula I is better than formula II.