He was able to do this even in the difficult positions demanded by the part.

VOA: special.2010.03.07

Part of the problem with using operant conditioning with babies is it's difficult to get them to behave in any systematic way.

应用操作性条件作用的部分问题在于,很难使婴儿们按照系统的方式行动

耶鲁公开课 - 心理学导论课程节选

What do you think is the most difficult part about studying English in the UK?

你觉得在英国，学习英语最难的部分是什么？

巴西的英语老师 - SpeakingMax英语口语达人

The most difficult part,she says, is creating a good design.

VOA: special.2009.05.18

I want to say a little bit about the cost of vaccines because this is a part of what makes it difficult to accomplish what's usually our goal in a vaccine development, which is deliver the vaccine to every population in the world.

我想谈谈关于疫苗的成本,因为这是令我们的疫苗发展目标,无法得以实现的困难之一,这个目标就是将疫苗送至世界上每一个人

耶鲁公开课 - 生物医学工程探索课程节选

This may be the most difficult part of all.

VOA: standard.2009.12.27

"At least one of the bombers detonated in the deepest part of the underground which made it hugely difficult both to undertake rescue operations and to carry out the forensic examination of the site which needed to take place."

VOA: standard.2010.04.01

Some of the local residents in Searchlight did not like the fact that outsiders had come in to target Senator Reid, who faces a difficult re-election bid this year, in part,because of his work in guiding the divisive health care reform bill through Congress.

VOA: standard.2010.03.28