Question

1. We merely need to plug in to the same sources of power they yese in that day.

2. We merely need to plug in to the same sources of power they yese on that day.

(Which one is correct, 'in that day' or 'on that day'? Are both correct? Which one is popular?)

Answer 1

Rfvv, first, I think you mean "use" instead of 'yese'.

Then to answer your question... which on is correct will depend on what you want to say. If you are referring to a day in the distant past, then you may use "in that day". If you are referring to a time when the object worked when being plugged in, then you may use "on that day".