这是一个困难的问题。
The decision to search for birth parents is a difficult one to make.
作出寻找亲生父母的决定是困难的。
Curiosity, he argues, is the third key factor—and a difficult one to preserve.
他认为，好奇心是第三个关键因素，也是一个很难保持的因素。
But the problem is a difficult one to solve.
但这是一个难以解决的问题。
The question before us is a difficult one.
我们面前的问题是一个困难的问题。
The jump was a very difficult one.
这种跳跃是个非常难的动作。
The final exam will be a difficult one.
期末考试将会很难。
We come again with a difficult one, ok?
我们再来一首难点的，好吗？
This year has been a particularly difficult one for NASA.
对于美国航天航空局来说，今年是特别艰难的一年。
He plays admirably. His part is a very difficult one.
他的演技令人倾倒。他的角色是很难演的。收藏。
This decision was a very difficult one for me to make.
这对我来说是一个困难而重大的决定。
The situation he faced was an extremely difficult one.
他面临一个异常困难的形势。
The travel through the desert was a very difficult one.
那次穿越沙漠的旅行是非常艰难的一次旅行。
AA: Yes, this away game is going to be a difficult one.
是的，这场客场比赛将是一场艰苦比赛。
It's a difficult one. I think it's a good quote as well.
这是一件难事，我也认为这是一个好的引用。
However, writing is considered as the most difficult one.
尽管如此，写作一直被认为是其中最难的一项。
This year, though, has been a particularly difficult one for NASA.
然而，今年成了对国家航空航天局而言尤其困难的一年。
The last one but also the most difficult one is to surpass ourselves.
最后也是最难得一点是，就是如何超越自己。
What was the most difficult one to decide and how did you make your choice?
你作出的最艰难的决定是哪个？如何做的选择？
However, very often the second step, believe, can be the most difficult one.
然而，第二步：相信，总是最难的一步。
Humes problem is a quite difficult one in the history of philosophy of logic.
休谟问题是逻辑哲学上的一大难题。
This is a difficult one (and probably is for everyone), but it's essential for me.
这一点很难(大概对每个人来说都一样)，可是对我来说必不可少。
The problem of cathode design is the key and difficult one should be solved first.
阴极设计是电解加工首先要解决的问题，也是电解加工中难以解决的问题。
The traffic signal optimization is the most difficult one of intelligent transportation control.
交通信号优化是智能交通控制中的难点。
Word teaching in Junior middle school English is not only a key point, but also a difficult one.
单词教学在初中英语教学中既是一个重点，又是一个难点。
The most difficult one was that they could not concentrate attention and could not remember information.
其中最大的困难就是注意力无法集中和无法记住关键信息。
The most difficult one was that they could not concentrate attention and could not remember information.
其中最大的困难就是注意力无法集中和无法记住关键信息。
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