Yesterday, the guy I was conversing with, told me that he is good at speaking English. Hearing it, I asked him right away "why are we wasting our time speaking in Hindi. (no offence to my mother tongue).
As I said it, I felt that I should have added "by" before using "ing" for example: "why are we wasting our time by speaking in Hindi.
I looked it up on Google and found out that the ing here is a gerund. But I don't know when to use gerund . I could not fathom the appropriate usage of it as the rules have been vaguely described.
So my question is :
A. Is there any difference between these two sentences?
B. Can I use ing without by preposition without affecting the meaning?