If you have wide and keen interests and activities in which you can still be effective, you will have no reason to think about the merely statistical fact of the number of years you have already lived, still less of the probable shortness of your future.
1、still less of the probable shortness of your future是修饰the number of years，作定语吗？
2、教程上说这半句省略了，（you have）still less （reason to think ）of the probable shortness of your future。是如此吗？那关系代词在从句中干什么成分？
网友可以查词典，几乎每本词典都网站收录了这个词组。
still less：更不需要说；更何况。常用于否定句后。
比如：
He is not a scholar, still less a poet.
他不是一个学者，更不是一个诗人。
We fear no death, still less difficulties.
大家死都不怕，何况困难。
【注意】有时，后面接of 是承前省略了有关成致使的。比如：
He knows little of mathematics, and still less of chemistry.
他几乎不懂数学，更不需要说化学了。
教程上说这半句省略了，（you have）still less （reason to think ）of the probable shortness of your future。是如此吗？那关系代词在从句中干什么成分？
【答】是的。但没定语从句，自然就没关系代词的说法。
