You could use the 'find and replace' function of your word-processing program. Set it to search for every occurrence of two spaces, and replace each set with single spaces.
no spaces
Spaces can mess it up and according to formats such as MLA it needs to be a tab. If the paper is printed off you might not be able to tell but if it is emailed the formal of it might be changed with spaces.
In typing, proper style is 2 spaces after a period (.), as well as after a colon (:).
2 Spaces
Spaces are not words. Nor do you type spaces into words. Spaces separate words.
To end one sentence and begin another, a period must be inserted between the two, along with one to two spaces.
He left blank spaces in the periodic table in the correct grouping and period that is where the newly discovered elements were placed.
Because of how the program is written you need to use punctuation instead of spaces.
It used to be 2 spaces but nowadays it is only 1.
A form
a form
I only type one space after a period. It is the standard practice in modern writing.