We didn't understand how difficult it was to distribute a national paper.

我们不明白配销一份全国性的报纸有多么困难。

《柯林斯英汉双解大词典》

There are many varieties and grades of paper materials, and whilst it is fairly easy to spot the varieties, it is far more difficult to spot the grades.

纸张材料有许多品种和等级，虽然很容易分辨它们的种类，但要分辨它们的等级就困难得多了。

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Paper cutting sounds very easy but it can be difficult.

剪纸听起来很简单，但其实很难。

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Because writing a philosophy paper is a difficult thing to learn how to do.

因为写哲学论文,是不太好学的。

耶鲁公开课 - 死亡课程节选

Can you tell us about the most difficult assignment or paper that you've had to do?

你能给我们讲一讲你最难的一次任务或者论文吗？

考试考砸了怎么办 - SpeakingMax英语口语达人

He says not only are the logistics of installing paper ballots difficult, he doesn't know why advocates think it's an improvement.

NPR: Local Election Officials Oppose Paper Ballots

These rules look fine on paper but are difficult to enforce.

ECONOMIST: International adoptions are not always for the best

He said he would not "paper over the difficult decisions" but maintained the party had had several victories in government, including more apprenticeships and more free childcare.

BBC: Nick Clegg reveals he was given a 'big green onesie'