这是著名的“李约瑟难题”。

This is the famous Needham <em>difficult</em> <em>problem</em>.

他在苦思解决那个难题的方法。

He was wrestling with the <em>difficult</em> <em>problem</em>.

在开始的时候存在一个难题。

At first there was a seemingly <em>difficult</em> <em>problem</em>.

只有小高斯能解决这个难题。

Only little Gauss can solve the <em>difficult</em> <em>problem</em>.

如何搭建木架，是一道难题。

How to build wooden stand , is a <em>difficult</em> <em>problem</em>.

他很快把注意力转到这个难题上。

He soon turned his attention to the <em>difficult</em> <em>problem</em>.

这一直是部门预算中的一个难题。

This has been in a departmental budget <em>difficult</em> <em>problem</em>.

举一个你解决过的智力难题。

Gimme an example of an intellectually <em>difficult</em> <em>problem</em> you solved?

律师的劝告帮助解决了这个难题。

The lawyer's advice led to the resolution of this <em>difficult</em> <em>problem</em>.

为了解决那道难题,他试了各种方法.

He tried all manner of ways to solve the <em>difficult</em> <em>problem</em>.