keep on or go on?

[leolya]

What is the difference between keep on and go on (CONTINUE)? I can't get when I can use "keep on" or "go on"?
For example, why I have to use "keep on" here: "My sister kept on asking me question after question."? Why not "go on"???
"She can’t go on pretending that everything is okay when it clearly isn’t." Why not "keep on"??? And so on.
Thank you very much! :)

[Amy]

What is the difference between keep on and go on (CONTINUE)? I can't get when I can use "keep on" or "go on"?
For example, why I have to use "keep on" here: "My sister kept on asking me question after question."? Why not "go on"???
"She can’t go on pretending that everything is okay when it clearly isn’t." Why not "keep on"??? And so on.
Thank you very much! :)

go on

To take place; happen: didn't know what was going on.

To continue: Life must go on.
To keep on doing (something): Don't go on talking.
To proceed: She went on to become a senator.
Informal To talk volubly: My, you do go on.

keep on

Continue, persist, as in They kept on singing all night. [Late 1500s]

Maintain an existing situation, as in After Mr. Brown died, the housekeeper wondered if she would be kept on. [Mid-1600s]

Cause to stay on or remain attached, as in Keep your coat on; it's cold in here. [Late 1800s]

I found the above from
http://dictionary.reference.com/search?q=keep%20on
http://dictionary.reference.com/search?q=go%20on

[Coffa]

What is the difference between keep on and go on (CONTINUE)? I can't get when I can use "keep on" or "go on"?
For example, why I have to use "keep on" here: "My sister kept on asking me question after question."? Why not "go on"???
"She can’t go on pretending that everything is okay when it clearly isn’t." Why not "keep on"??? And so on.
Thank you very much! :)

You can use either "go on" or "keep on" in both of the sentences you have quoted. The difference is one of emphasis.

"My sister went on asking me question after question." is a neutral expression, conveying a repetitive action.

"My sister kept on asking me question after question." has the same basic meaning, but carries an association that the activity continued beyond what was normal or reasonable.

The essential difference can be conveyed by substituting the verb "continue" for "go on", and "persist (in)" for "keep on". For example:

1). "She can't CONTINUE (go on) pretending that everything is okay when it clearly isn't."

OR

2) "She can't PERSIST IN (keep on) pretending that everything is okay when it clearly isn't."

Note that you must be careful with these phrases, because some verbs require the gerund form always (eg "She keeps (on) pretending that...", but not "She keeps (on) to pretend that..."), some verbs require the infinitive form always (eg "She needs to pretend that...", but not "She needs pretending that..."), and still others can use either form (eg "She continues pretending that..." or "She continues to pretend that..."). If in doubt, choose the third type where possible - "TRY to CONTINUE REMEMBERING that you should PREFER verbs like START or BEGIN" - all of the verbs in that sentence can use the gerund or infinitive.