A clumsy question: why not "existing" in this sentence?

the word must agree with "the percieved risk"

say these out loud:

the percieved risk exists
the percieved risk exist
the percieved risk existing
the percieved risk existed

exist does not make sense

existing and existed do not fit the tense of the sentence

exists is the only one that fits the tense and agrees with "the percieved risk"

"Risk" is a singular noun (subject); hence it requires "exists" a singular verb (predicate).

Thank you so much!

bluestblue, your alternative, "than there's existing," is acceptable grammatically as far as i know, but the "correct" version, "than exists," is better because it uses fewer words to say the same thing.

Thank you Yitwail!
I think the "is" in "...than what is excising..." shouldn't be omitted anyway. Because its tense is different from the main clause. Am I right?

And still I think in this segment "... than what exists in the public mind today", what stands for "the anxiety", not stands for "the perceived risk". Puzzled.

******

I have asked a lot of questions and have got a lot of help from your guys. I hope my questions won't offence the regulations of this forum.
I really love this site.

I assume you mean existing but I still don't see this statement being made anywhere, so I'm not sure what you're referring to.



Ok, it stands for "anxiety over the perceived risk of getting cancer," I see how my example was misleading.

You're welcome. i'm not sure either exactly what you're asking, but if you're talking about your sentence,



then you did not omit an is because there's is a contraction for there is. you also switched "there" with "what" so then the sentence would be

There ought to be less anxiety over the perceived risk of getting cancer than what's existing in the public mind today.

you maybe got confused by 's used as a contraction for is, and 's used to make a possessive noun. for example, in the sentence

Tomorrow's Tom's birthday.

the first 's is a contraction, and the second makes a possessive noun, so the meaning is

Tomorrow is Tom's birthday.