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题库 / Prep2007E1-SC-124
Whereas the use of synthetic fertilizers has greatly expanded agricultural productivity in many parts of the world, an increase in their use can create serious environmental problems such as water pollution, and their substitution for more traditional fertilizers may accelerate soil structure deterioration and soil erosion.
an increase in their use can create serious environmental problems such as water pollution, and their substitution for more traditional fertilizers
an increase in their use can create serious environmental problems like water pollution, and if substituted for more traditional fertilizers, it
if these fertilizers are used increasingly, they can create serious environmental problems such as water pollution, and if used as substitutions for more traditional fertilizers, they
the increased usage of these fertilizers can create serious environmental problems such as water pollution, while if substituted for more traditional fertilizers, this substitution
the increased usage of these fertilizers can create serious environmental problems like water pollution, while their substitution for more traditional fertilizers
...BUT the sentence keeps going! The clause beginning with "while if substituted" clearly *means* "if [synthetic fertilizers are] substituted, but nowhere in the sentence has "synthetic fertilizer" been the SUBJECT of a verb. That phrase only appears as a modifier (in the nonunderlined portion). D has a definable, structural grammar issue--so this choice is out.
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