You can as the previous post suggests use the search and
replace option.
Another method available in the grammar checker allows for
setting, 1, 2, or don't check. I think this is also
available under auto correct, but can't find there at the
moment.
Click Tools | Options; and select the spelling and grammar
tab.
....at the bottom of the tab click settings.
In the popup dialog, look at the very top for spaces
required between sentences, and set it to one (1).
If you don't wish to check the entire document for
grammar, deselect the checkboxes that you don't want to
apply when you run the grammar checker.
Hope this helps
jesse