Sentence examples for proved difficult to explain from inspiring English sources

On Sunday, Ed Gillespie, a senior adviser to Mr. Romney, told CNN that the candidate had "retired retroactively" from Bain more than two years after leaving in 1999, an example of how the complexity of Mr. Romney's business has proved difficult to explain in the simple terms favored by political campaigns.

Morally, it is the right thing to do — although that may prove difficult to explain to the Minutemen and their supporters.

It has proven difficult to explain why this "double luck" prevents knowledge.

This observation has proven difficult to explain by geologists attempting to build predictive models for the formation over the last two decades.

It's nice the Nebul.us has two very different use cases, but I'm concerned it may prove difficult to explain them both to new users who stumble across the site (frankly I was pretty confused at first).

This may explain why it proved difficult to elicit answers beyond standard answers concerning the weaknesses and challenges in case identification, particularly in the SSIs.

The reason why it has proved difficult to develop an HIV vaccine can be explained in this context.

Outside the church, Brazil does not have much of a charity culture, which may explain why it has proved difficult to recruit volunteers.

Neutrality proved difficult to maintain, though.

Alas, it proved difficult to find.

Genocide has proved difficult to prosecute.