The phrase "a certain time the" is not correct and does not make sense in written English.
It seems to be an incomplete thought and lacks clarity, making it unusable in its current form.
Example: "At a certain time the meeting will begin."
Alternatives: "at a specific time" or "during a particular time".
If at a certain time the frequencies of A1 and A2 are p and q, respectively, after one generation the frequency of A1 will be p1 = p − pm + qn.
"This is an extreme event in terms of urban infrastructure, but the event was predictable and known — I knew if it hit at a certain time, the subways were flooded," he said.
With him, pictures were also self-exploration, a record of his feelings and experiences on a certain day at a certain time, the equivalent of the journals and personal letters that men and women were only just beginning to write.
The mortgagor (debtor) conveyed the ownership of land to the mortgagee subject to the condition that, if the mortgagor repaid a debt he owed the mortgagee by a certain time, the mortgagee would reconvey the land to the mortgagor.
After a certain time, the voltage is ramped up rapidly to a certain voltage V ′.
After a certain time the temperature balance level (343°C) is reached again.
At a certain time of the year, the epitokes swarm to the ocean surface and engage in mass shedding of eggs and sperm.
By Italo Calvino At a certain time in the morning, the prisoners' wives began to arrive and started gesturing, their faces turned up toward the windows.
At a certain time in the morning, the prisoners' wives began to arrive and started gesturing, their faces turned up toward the windows.
The propagation of seismic waves in the fractured medium at a certain time disturbs the enhanced permeability of the fractures.
Furthermore, our HEBFC had stable cycle operation and could keep high power output for a certain time as the result of the regeneration of Ag2O.
