Is the phrase "during which period" grammatically acceptable to use in a sentence?
As in "It was during which period I did blah blah blah."
thanks in advnce
No. You could reword your sentence to use 'which' as an interrogative
During which period did I . . .
or the object of a prepostion:
It was during the period in which I . . .
But these would change the meaning of the sentence.