关于主语比较？

shala

请问各位，在比较主语时，是否都要补出谓语助动词？
补出的助动词是否都要前置？有几个例题没看明白：
    1 Several studies have found that the cornoary patients who exercise most actively are at least fifty percent less likely than those who are sedentary to die of a heart attack.
    2 Inuit of the Bering Sea were isolate from contact with Europeans longer than were Aleuts or Inits of the North Pacific and northern Alaska.
    3 Los Angeles has a higher number of family dwellings per capita than does
any other large city.
    4 Because natural gas is composed mostly of methane, a simple hydrocarbom,vehicles powered by natural gas emit less of vertain polllutants than those burning gasoline of diesel fuel.
    为什么第2，3题补出，而第1，4题没补出？
    多谢赐教！！！[em13]

shala

thanks a lot!!

Louisa_xy

2. were isolate from contact with  longer than were and northern Alaska.
如果不补出谓语动词 were,就会造成歧义。不知是比较Inuit of the Bering Sea 和Aleuts or Inits of the North Pacific，还是比较Europeans和Aleuts or Inits of the North Pacific。

3 Los Angeles has a higher number of family dwellings per capita than does
any other large city
does可有可无，因为没有does，也不会造成歧义。

1/4 题，也是这样，没有补出谓语动词，都不会有歧义。
谓语动词的位置，可以放在主语前也可以在主语后。