Today,the solution to the problem is so common that it is difficult to understand that there was a problem at all.

VOA: special.2010.07.14

It's a difficult problem that not everyone is smart -they vary in their ability -so we try to make a world in which it's pretty safe for the small investor who's not paying attention.

不是所有人都是聪明人,这是个难题,大家能力不同,所以我们试图营造一个环境,一个让小投资者感到安全的环境,而无需忧心忡忡

耶鲁公开课 - 金融市场课程节选

It shouldn't be difficult to see a kind of problem that is beginning to arise in Milton's text here.

这是一个很容易看出的问题,在弥尔顿的作品中也被提了出来。

耶鲁公开课 - 弥尔顿课程节选

She began to explain to the students how to solve a very difficult problem.

VOA: special.2009.10.25

In fact there's research-- for example, this was done with internists, doctors, who are giving a very difficult, very difficult question connected to a liver problem that an individual patient had.

实际上有这样一项研究-,在内科医生，医生中间进行，向他们提出一个，与肝脏问题有关的很困难的问题,那是一个病人的病症。

哈佛公开课 - 幸福课课程节选

She was never willing to leave a problem unfinished, even difficult problems in mathematics.

VOA: special.2009.11.08

Hobrooke admits is a very complicated and difficult problem to address.

VOA: standard.2009.06.15