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]作者: Louisa_xy 时间: 2003-2-5 16:03
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。
