Question from GMATPrep

yaoyao99

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.

B. an increase in their use can create serious environmental problems like water pollution, and if substituted for more traditional fertilizers, it
C. 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
D. the increased usage of these fertilizers can create serious environmental problems such as water pollution, while if substituted for more traditional fertilizers, this substituion
E. the increased usage of these fertilizers can create serious environmental problems like water pollution, while their subsitution for more traditional fertilizers

I picked C but the answer is A. What I don't understand is 1. Shouldn't it be their usage instead of their use?  2. their substituted sounds ambiguous.  "if used as substitution for other fertilizers" is much more clear.

[此贴子已经被作者于2006-6-12 10:46:29编辑过]

lesterlau

I've looked up Cambridge Dictionary:

Usage: 
        the way something is treated or used
e.g. Sports equipment is designed to withstand hard usage.

Use: [C or U]
                a purpose for which something is used
e.g. A food processor has a variety of uses in the kitchen.

在这里前面用了the use of fertilizers,，后面说的是同一件事，所以也是要用the use，而不是usage。在A选项中，their指的是synthetic fertilizers，但在C选项中，最后的they有歧义

yaoyao99

Ah, thanks a million plus one!! 

ly365

whereas...if... i have never seen this construction.