求助个Than前后一致的问题
近来写文章被这个搞晕了，than前后比较的东西应该是对等的，但看文献里面有一些than后面用了does，有一些没有，谁能给我讲解一下，谢谢了。投文章审稿人说我的英语需要找人润色一下。
下面是文献里面摘的一些例句：
These catalysts exhibit increased thermal stability and produce higher molecular weight polymers than conventional metallocene catalysts
18-ZrCl/MAO produces polyethylene with a higher molecular weight than 18-ZrMe/B2
ethylene-bridged catalyst 19-ZrMe is more active than methylene-bridged catalyst 18-ZrMe
18-TiMe/B2 and 19-TiMe/B2 exhibit∼65X and∼35X greater polymerization activity, respectively, than does the monometallic catalyst 20-TiMe/B1
catalyst 19-TiMe enchains 15.4% more styrene than does 20-TiMe/B1.
calculated reactivity ratios indicate that binuclear catalyst 19-TiMe/B2 favors styrene insertion more than does catalyst 20-TiMe/B1
Single-component Ni(II) catalyst 33 (Chart 17),86 based on a 3,30-bisalicylaldimine ligand, yields polyethylene with lower activity than the mononuclear Ni(II) Grubbs’ catalyst
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These catalysts exhibit increased thermal stability and produce higher molecular weight polymers than conventional metallocene catalysts（后面跟的句子结构 “exhibit。。。。。。”因为重复省略）
18-ZrCl/MAO produces polyethylene with a higher molecular weight than 18-ZrMe/B2 (后面跟的句子结构 “produces ......同上，省略）
ethylene-bridged catalyst 19-ZrMe is more active than methylene-bridged catalyst 18-ZrMe 后面跟的句子结构 “is..........."同上，省略）
18-TiMe/B2 and 19-TiMe/B2 exhibit∼65X and∼35X greater polymerization activity, respectively, than does the monometallic catalyst 20-TiMe/B1 (does 代表前面的 “exhibit”，省略后句子结构倒装）
catalyst 19-TiMe enchains 15.4% more styrene than does 20-TiMe/B1. (does 代表前面的 “enchains”，省略后句子结构倒装）
calculated reactivity ratios indicate that binuclear catalyst 19-TiMe/B2 favors styrene insertion more than does catalyst 20-TiMe/B1 (does 代表 “favors”，省略后句子结构倒装）
Single-component Ni(II) catalyst 33 (Chart 17),86 based on a 3,30-bisalicylaldimine ligand, yields polyethylene with lower activity than the mononuclear Ni(II) Grubbs’ catalyst （后面跟的句子结构 “yields。。。。。。”因为重复省略），
啊，我的问题是为什么有的省略了，有的加了个does，does不可以省略吗？
可以省，可以省，取决于作者认为后面的省略是否清晰，但其实省不省都一样。只要主语有同质性可比性都可以省