"I am sure it was her car outside. So she must have been at home."

[ambitious-girl]

Hi,

Are these two sentences equivalent, and is "so" coordinating conjunction in both sentences? I have always learned to use "so" in the second form.

"I am sure it was her car outside. So she must have been at home."

"I am sure it was her car outside, so she must have been at home."

 

[ambitious-girl]

Yes, they are equivalent, and yes, 'so' is a coordinating conjunction in both cases. Irrelevant, but I prefer the second.

Thanks RoberJ.
Can I use the first one in an academic writing like IELTS?

 

[Rover_KE]

I would only use the second. I consider the first to be ungrammatical.