“3+1”簡單造句，3+1造句子

It suggests that it is better to use domestic catalyst for "3+2" conversion and the imported catalyst for "3+1" conversion.

並建議：採用國產催化劑時宜選用“3+2”五段轉化；採用進口催化劑時可選用“3+1”四段轉化。