"influence" (a verb) vs "have an influence on"

[mrwroc]

When should I use "influence" (a verb) and when "have an influence on".

For example, can I write:
Helen badly influences him. AND Helen has a bad influence on him.
?

I can't imagine any example where only one form is correct. I think the same situation is with "impact (on)" and "have an impact on".

 

[GoesStation]

Helen badly influences him. :cross: AND Helen has a bad influence on him. :tick:

I can't imagine any example where only one form is correct.

You've already found one!

I think the [STRIKE]same[/STRIKE] situation is the same with "impact (on)" and "have an impact on".

The present simple just doesn't work there, even for those who use "impact" that way (which I emphatically don't recommend).

 

[emsr2d2]

I can't speak for other variants, but in BrE the second would usually be expressed as "Helen is a bad influence on him".

 

[GoesStation]

On the other hand, "Helen influences him badly" is grammatically correct. It doesn't really make sense though; does it mean she does a poor job of it?