In the past this process of transition has often proven difficult.

在过去，这种转变过程常证明是艰难的。

《柯林斯英汉双解大词典》

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Reducing demand has proven difficult.

事实证明，降低需求非常困难。

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O'Neill told the Racing Post how City Affair had proven difficult to control, even before it unseated him.

BBC: SPORT | Other Sport... | Horse Racing | O'Neill sorry for butting horse

Although this task has proven difficult, Lenovo has clearly found a modus vivendi.

FORBES: Lenovo, Former IBM PC Company, Is Kicking Butt

Repatriation has proven difficult almost everywhere: people are traumatised by their experiences, distrustful of neighbours and reluctant to return.

ECONOMIST: Exporting misery | The