The key to the problem is that we don not have enough money.

问题的关键是我们没有足够的钱。

youdao

The key to the problem is to assure the stability of water ring.

保证水环的稳定性是水环输送的关键。

youdao

The key to the problem lies in the constitution of the outline for city design.

解决这一问题的关键在城市设计大纲的制定上。

youdao

Now, as obvious a statement as that is in this algorithm, it turns out that is the key to this whole problem being solved correctly without my algorithm looping infinitely.

这是此算法中很明显的一句话，也是正确解决,整个问题的关键,否则此算法就会陷入死循环。

哈佛公开课 - 计算机科学课程节选

Russia lost no time in claiming that Chechnya was the key to the problem.

BBC: The Dagestan connection

In short, if subject matter expertise were the key to solving the problem, the organizations we work with would have already solved it.

FORBES: Insight Labs on How to Solve the World's Toughest Challenges

Often the goal is to find the key indicator of a problem or to track the performance of a system.

FORBES: Splunk's Godfrey Sullivan on Overcoming Barriers to Operational Intelligence