语法正确?Such knowledge is a true gift, for all that it is painfully won,
全句：Such knowledge is a true gift, for all that it is painfully won, and it has been worth more to me than any qualification I ever earned.
其中“for all that it is painfully won,”是不是is应该不要?如果我理解错误,请帮忙分析句子结构.谢谢!