I thought you might be setting him an impossible task.

But anyone sitting in a committee meeting knows that can be a difficult and perhaps impossible task.

This would not be an impossible task, given the state of information technology.

The come back was seen as an almost impossible task.

"Sometimes I think running a hospital is an impossible task."

But of course then we get to an almost impossible task.

Why did everything become an impossible task with these two?

Little did he know it was to be an impossible task.

This fact alone made their task difficult if not impossible.

Your father has set me this time an impossible task.