The teacher spoke to the students, saying, “A man rises and walks. What does this tell you?”
Bumbo answered, “A man is his actions.”
Bumbo rushed to his desk and started erasing commas.
The teacher’s sentence illustrates that a man can do more than one action. As Bumbo realizes, a man can do actions. In the same way, the subject of the sentence can have more than one predicate. If Bumbo puts a comma before the second predicate, he separates the subject from one of its actions. He already knows that the subject should not be separated from the predicate, so he rushes to find and erase any commas before the second predicate. When he erases those commas, he connects the subject to its actions.
According to Zen Comma Rule AJ, we don’t use a comma to separate the subject from the predicate. This is still true if the sentence has a compound predicate, as in the following example.
The files you sent were infected with some sort of virus and could not be opened on our system.
The subject is files. This subject has two predicates. The first predicate is were infected with some sort of virus. The second predicate is could not be opened on our system. The subject files, therefore, has two actions. We see that this is true when we break the sentence into two sentences.
The files you sent were infected with some sort of virus.
The files you sent could not be opened on our system.
Because the two predicates are a bit long, some writers will mistakenly put a comma after virus, which is the last word of the first predicate. This breaks Zen Comma Rule AK: Don’t use a comma to separate two parts of a compound predicate.
If we put a comma there, we separate the second predicate from the subject, thus breaking two commas rules at once.
Need help with commas? Get Zen Comma, an instructive reference guide on the 17 major uses and misuses of commas, available in PDF and Kindle formats. Read more about Zen Comma.