Looking on the internet deeply has found these results:

a man was walking his dog is the most popular phrase on the web.

a man were walking his dog 10 results on the web	a man was walking his dog 1406 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
It doesn't look like this phrase is very popular! The search could not find any examples on the internet.	A man was walking his dog through the graveyard when he saw another man crouching behind a gravestone. "Morning!" he said. The other man replies, "No, ... Oct 1, 2014 ... A man was walking his dog on 164th Street East when a car pulled up and a woman he recognized got out and grabbed the cellphone from his ... ... incident occurred on March 18, 2012, in the southern part of Fayette County in Pennsylvania. A man was walking his dog in a rural location at about 11:45 pm. On Thursday, May 14, 2014, in a wooded area on the campus of The University of Colorado, Boulder, a man was walking his dog on leash when it was attacked ...

a man were walking his dog

10 results on the web

a man was walking his dog

1406 results on the web

More popular!

It doesn't look like this phrase is very popular! The search could not find any examples on the internet.

A man was walking his dog through the graveyard when he saw another man crouching behind a gravestone. "Morning!" he said. The other man replies, "No, ...
Oct 1, 2014 ... A man was walking his dog on 164th Street East when a car pulled up and a woman he recognized got out and grabbed the cellphone from his ...
... incident occurred on March 18, 2012, in the southern part of Fayette County in Pennsylvania. A man was walking his dog in a rural location at about 11:45 pm.
On Thursday, May 14, 2014, in a wooded area on the campus of The University of Colorado, Boulder, a man was walking his dog on leash when it was attacked ...