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by metallicafan » Tue Nov 29, 2011 5:17 pm
Often visible as smog, ozone is formed in the atmosphere from hydrocarbons and nitrogen oxides, two major pollutants emitted by automobiles, react with sunlight.

a) same.
b) ozone is formed in the atmosphere when
c) ozone is formed in the atmosphere, and when
d) ozone, formed in the atmosphere when
e) ozone, formed in the atmosphere from

The sentence is easy. However, why "when" is correct in this case? According to Manhattan GMAT SC book, "when" must be used only to refer to periods of time such as 1999, "the Great Depresion", etc.
Please clarify.

OA is B.
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by amit2k9 » Tue Nov 29, 2011 9:01 pm
Ozone is formed when hydrocarbons and nitrogen oxides react with sunlight.
This is what the sentence states.

Notice the react with sunlight phrase.It requires the usage of 'When' as I have mentioned in the sentence previously.
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by metallicafan » Tue Nov 29, 2011 9:47 pm
amit2k9 wrote:Ozone is formed when hydrocarbons and nitrogen oxides react with sunlight.
This is what the sentence states.

Notice the react with sunlight phrase.It requires the usage of 'When' as I have mentioned in the sentence previously.
I think you did not understand my question. According to many sources, "when" can only be used to refer to dates, periods of time, not situations like this.

I want to know whether there is an exception. This is an official question.
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by arpita@gurome » Wed Nov 30, 2011 4:20 am
Manhattan GMAT is a trusted source, I doubt they would restrict the use of "when" to specific dates or events as you have mentioned in your example. If you observe carefully, "when" does refer to time even in this example: the time or the moment when hydrocarbons and nitrogen oxides react with sunlight.

Hope that helps. :)
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