I will say uncle to you.

我喊你叔叔了。

I tried three times, but I had to say uncle.

我试了三次，但我不得不放弃了。

I refused to say uncle no matter how they threatened me.

无论他们怎样吓唬我，我都不肯服输。

He refused to say uncle no matter how they threatened him.

无论他们怎样威胁他，他都不肯服输。

Never say uncle? But he apologized to me and promised that he would never hurt me again.

从不认错？但他向我道歉了，并且保证不会再伤害我了。