Sentence examples for proved difficult to delineate from inspiring English sources

Within Passerida, the superfamily Sylvioidea has proved difficult to delineate based on morphology, because of apparent multiple events of convergent evolution [e.g. [ 9- 12].

Spectacular early results proved difficult to sustain.

Yet reform proved difficult to implement.

The furlough plan proved difficult to enforce.

The advice proved difficult to follow.

The latter aim proved difficult to enforce.

Neutrality proved difficult to maintain, though.

Alas, it proved difficult to find.

Genocide has proved difficult to prosecute.

The effect proved difficult to measure.

Lying worked, but proved difficult to undo.