求解释~~~

寻沫访华

Though the law will require emissions testing of all diesel vehicles, fromtractor trailers to excursion buses, it will have no effect on sport utilityvehicles, almost all of which are gasoline powered, and will not be subjected to emissions-control standards as stringent as they are fordiesel-powered vehicles.

A.powered, and will not be subjected to emissions-control standards as stringent as they are for

B.powered, and therefore not subjected to emissions-control standardsthat are as stringent as those of

C.powered and therefore not subject to emissions-control standards as stringent as those for

D.powered, which are not subject to emissions-control standards asstringent as they are for

E.powered and therefore they are not subject to emissions-controlstandards as stringent as those of

我觉得therefore加在and后面怪怪的，是可以这个用法么，这个题为什么会选C呀

elizabeth630

thanks

benjaminzhang

The entire phrase " almost all...vehicles" is a single modifier modifying SUVs. Therefore adding comma after "powered" breaks part the modifier and create a run-on structure.

Here you can eliminate ABD

in E "...and therefore they are not..." here, the pronoun "they" is redundant and unclear so E is incorrect

C is correct. The modifier contains 2 independent ideas "gasoline powered and not subject to control". Do a simple test, take out the connector "and" and break up the 2 ideas into separate modifier:" almost all of which are gasoline powered" "almost all of which are not subjected to emission control". if you say "almost all of which are will not be subjected", the sentence doesn't make sense.

in essence this is parallelism, you have to make the 2 ideas"gasoline powered" and "not subjected to control" parallel

note: "which" is the pronoun clearly referring to SUVs