"When" Vs "in which"

[goelmohit2002]

Hi All,

For the below question, as per the explanation given in OG-11 for Q#59....

" "in which" and "when" can be used interchangeably in this sentence".

But as per my understanding "which"

a) generally refers to physical things or
b) as a middlemen as suggested by Manhattan.

Can somebody please tell, how "in which" is correct here when none of the above is the case. Are there specific cases when "in which" and "when" can be used interchangeably?

===================
His Studies of ice-polished rocks in his Alpine homeland, far outside the range of present day glaciers, led Louis Agassiz in 1857 to propose the concept of an age in which great ice sheets had existed in now currently temperate areas.

A. in which great ice sheets had existed in now currently temperate areas.
B. in which great ice sheets existed in what are now temperate areas.
C. when great ice sheets existed where there were areas now temperate.
D. when great ice sheets had existed in current temperate areas.
E. when great ice sheets existed in areas now that are temperate.

Thanks
Mohit

[mals24]

'which' and 'in which' are not the same. The addition of 'in' changes the meaning.

'in which' actually means 'inside which' or 'during which'
'in which' is used to define a location or a time period.
The era in which the church influenced the actions of the people.

'Which', on the other hand, as you pointed out refers to physical things or middleman. The table, which is 10 years old, belongs to my aunt. Here which refers to a physical thing table.

However in this question 'in which' refers to the age or defines the age during which the ice sheets existed.

Hence in this sentence 'in which' and 'when' can be used interchangeably because they both refer to a time period or a certain age in history.

[goelmohit2002]

Excellent explanation Mals. Thanks for the clarification.

[svishal1123]

I had another doubt in this question.

Why cannot existed be in Past Perfect tense (had existed)?

There is already a verb in the past tense in the sentence and the verb in question (exist) occurred much before that.

[svishal1123]

And I have exactly the same doubt in question 75 from OG 11.

Any response is really appreciated. Thanks.

Question 75:

Salt Deposits and moisture threaten to destroy the Mohenjodaro excavation in Pakistan, the sie of an ancient civilization that flourished ( why not had flourished) at the same time as the civilizations in the Nile delta and the river valleys of the Tigris and Euphrates.[/b]

[scoobydooby]

svishal1123,

past perfect is used for the earlier of two past events.

for Q75: The Mohenjodaro civilization and the Nile delta civilization are both past events that happened at the same time. so we cannot use the past perfect "had flourished". simple past is thus used.

[KICKGMATASS123]

What's the OA?

I think it's A based on the explanations..