我不知道他是否敢试一试。用英语怎么说？

我不知道他是否敢试一试。

I don't know whether he dare try.

know

v. 知道，了解，认识，确信；n. 知情；

例句
I know you're above me socially, but I must say I find your attitude offensive...
我明白你的社会地位比我高，但我得说我觉得你的态度很粗鲁。

whether

conj. 是否，无论；

例句
They had their tablets analysed to find out whether they were getting the real drug or not.
他们将药片拿去化验以查明他们得到的是否是真药。

he

pron. 他，它，一个人；n. 雄性动物；

例句
Logic had prevailed and he had abandoned the idea.
最终理智占了上风，他打消了那个念头。

dare

vt. 敢，敢做，激（某人做某事），问（某人）有没有胆量（做某事）；vi. 敢，敢于，大胆，无畏于；aux. 敢，竟敢；n. 激将，挑战；

例句
I dare say he did as he was bidden.
我敢说他按照要求做了。

try

vt.& vi. 试图，努力，实验，审判，考

例句
He stopped to try to adjust his vision to the faint starlight...
他停下脚步试着让眼睛适应微弱的星光。