answer on vs answer for ,answer to or answer

[ostap77]

1)"Blair aides now acknowledge there is a case to answer on the failure to find the weapons, but they're being coy about just how far he will go."

Would there need to be "to answer for" for " to answer on"? Can I use "to answer on a question" for "answer to/a question"?

 

[bhaisahab]

1)"Blair aides now acknowledge there is a case to answer on the failure to find the weapons, but they're being coy about just how far he will go."

Would there need to be "to answer for" for " to answer on"? Can I use "to answer on a question" for "answer to/a question"?

They acknowledge that there is a case to answer, on the failure to find the weapons, but they are being coy about it.

 

[ostap77]

As to whether I can use "to answer on a question" for "to answer to/a question", wouldl it be grammatical?

"Well, in -- in most cases -- and, Bob, this is the last question I'm going to answer on this." Would it mean here "about this" or "to this"?