What's the difference between "have an effect on~" ," have an impact on~","have an influence on~"?
I studed these expressions have a same meaning. But I think these could have some difference to use. Am I right? When can i use these expressions separately or they are completly same?

Question

What's the difference between "have an effect on~" ," have an impact on~","have an influence on~"? 
I studed these expressions have a same meaning. But I think these could have some difference to use. Am I right? When can i use these expressions separately or they are completly same?

Answer

Look up www.the freedictionary.com

Answer

Well, check out the words, effect, impact, and influence, in the dictionary. That should tell you all you need to know.

They may be similar, but they're not the same.