Hi Sergon, Welcome to the Forum. According to time, what sounds normal and what sounds wrong or unusual: 1 'during a long period',No 2 'for a long period',Yes 3 'time interval between …', yes. Or just 'time between'.
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Clive According to time, what sounds normal and what sounds wrong or unusual:
1 'during a long period',No
This seems fine. In The New York Times:
http://query.nytimes.com/gst/fullpa