The duration of previous geologic periods was difficult to determine.

以前很难确定地质期的持续时间。

youdao

With such a long interval, it is difficult to determine the age of this fossil.

时间隔得这么久了，很难确定这化石的年代。

youdao

Outsiders may then find it difficult to determine your contributions and strengths.

局外人可能会很难确定你的贡献和优势。

youdao

and NATO forces even as the Obama administration prepares to send an additional The hazy groups and alliances of what collectively comprise the Taliban make it difficult to determine just who the U.S.

VOA: standard.2009.03.11

However, their young age makes it difficult to determine whether this is definitely the case.

BBC: Conjoined twins separated by Great Ormond Street doctors

The secrecy makes it difficult to determine how often such court orders are used.

WSJ: Court Order Seeks Email Data of WikiLeaks Volunteer Jacob Appelbaum

Xinhua news agency's Seoul correspondent says North Korea's reaction is "difficult to determine".

BBC: China media: Korean tensions