主句:.I am far luckier than most men,
原因状语从句：for I have been able since boyhood to make a good living doing precisely what I have wanted to do --
what I would have done for nothing,and very gladly,if there had been no reward for it.作what I have wanted to do 的补充,相当于定语从句．
2．没有什么表演,无论它怎么好,能够想象地永远保持一流的水平