instruction: Is the next sentence syntactically and semantically acceptable?

This needs investigating the problem.

response: unacceptable

instruction: Is the next sentence syntactically and semantically acceptable?

I have wanted to meet for many years the man who spent so much money planning the assassination of Kennedy.

response: acceptable

instruction: Is the next sentence syntactically and semantically acceptable?

Who seems to be certain to leave first?

response: acceptable

instruction: Is the next sentence syntactically and semantically acceptable?

You have presented so elegant a solution that we can only admire it.

response:
acceptable