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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
B选项的it只能指代一个单数，前面合理的单数是use，再带入到if substituted for...,就变成了if the use of synthetic fertilizers is substitued for for more traditional fertilizers， 这是错误的。 synthetic fertilizers才能被取代成traditional fertilizers， the use 不能被取代，所以B错。
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