English punctuation, comma problem, there is no talking sentence behind, why use comma? It doesn't seem to be used in Chinese. What about English?

"We are nothing but clocks," someone once said.

This is a whole sentence. Quotes are direct references. Use commas, because the sentence is not completely over. If you put the speaker first, you will use a period. Some people say, "We are just slaves of the clock."

When the speaker is at the back, the quotation marks in front can be commas, exclamation points, question marks, but not periods. Because the sentence is not over yet.

"Did you go to school yesterday?" Tom asked.

"What a nice day!" He shouted.