The phrase "impossible to suggest" is grammatically correct and can be used in written English.
It is often used to describe something that is not able to be recommended or proposed. Example: It was impossible to suggest a solution to the complex problem as there were too many variables to consider.
It would be politically impossible to suggest in public, for example, that women have the right to choose their sexual partners.
It is impossible to suggest that there is a safe way to use drugs without making it seem as if drug use is something we are willing to accept.
The only thing that's impossible to suggest in our present political climate is that we end this idiotic war.
During their various treatments, past and present, it would be nearly impossible to suggest that they should be carrying on their full duties within the Senate.
1. Shifting Endgoals -- In 2006, it would have been impossible to suggest that anything other than content knowledge was the desired endgoal of a quality education.
Until and unless this is established, it would be impossible to suggest a falsifiable hypothesis of how GAs work.
Elam told The Huffington Post that the post was intended as provocative satire to highlight how, in his opinion, it is impossible to even suggest that women take measures to protect themselves without being attacked for victim blaming.
It is difficult, if not impossible, for respondents to suggest solutions for problems they didn't know they had or evaluate something that is beyond their comprehension.
The tail was nearly impossible to bend, suggesting that it was not used as a paddle for swimming, as was once thought.
Other reports, impossible to confirm, suggested Isil had been driven from its base close to a key border crossing with Turkey.
And yet that thing is impossible to ignore, suggesting as it does a futuristic city with vertical as well as horizontal mobility.
