Sentence examples for this is unknown from inspiring English sources

This is unknown territory.

The environmental and health impact of this is unknown.

None of this is unknown to people who are familiar with Yahoo.

That this is unknown to its chief judges may be yet another sign of an unmanageably oversized circuit".

This is unknown territory at Roland Garros for Cilic too, who previously had won only one match here.

How is it going to recover from day to day to day? "All this is unknown," he said.

"This is unknown territory," admitted Cook.

However, the reason for this is unknown.

The impact of this is unknown.

The precise mechanism for this is unknown.

This is unknown because it is as yet undecided.