It's a difficult question to decide.是什么意思？

It's a difficult question to decide.

这是个难以决定的问题。

difficult

adj. 困难的，难做的，难解的，不易相处的；

例句
It is a difficult job and they should be paid accordingly...
这是份棘手的工作，他们应得到相应的报酬。

question

n. 问题，疑问，怀疑，议题；vt. 问（某人）问题，对（某事物）表示[感到]怀疑；

例句
...certain assumptions which are accepted without question as absolute truths.
某些未经质疑就被作为绝对真理而全盘接受的假设

to

prep. 向，朝着，到，关于，属于；adv. 朝一个方向的，到某种状态，关闭；

例句
I suggest you leave it to an expert...
我建议你把它留给专家来解决。

decide

vt. 决定，决心，解决，裁决；vi. 决定，下决心；

例句
In the absence of a will the courts decide who the guardian is.
在没有遗嘱的情况下，由法庭指定监护人。