下列对人类生命独特性的理解正确的是（  ）
①每个人都是独一无二的，因此应该我行我素                       ②每个人都有独特的成长道路，不应一味模仿别人
③认真分析自己的个性特点，选择适合自己的成才之路       ④走自己的路完全由自己决定，不考虑别人的意见

“既以非之”一句中的通假字是____，它的意思是____。

“天下之难物于故也”一句中的通假字是____，它的意思是____。

求1+2+2²+2³+ +2²⁰¹²的值，可令S=1+2+2²+2³+…+2²⁰¹²，则2S=2+2²+2³+2⁴+…+2²⁰¹³，因此2S﹣S=2²⁰¹³﹣1．仿照以上推理，计算出1+5+5²+5³+ ...+5²⁰¹²的值为（   ）

Jack is a clerk of a bookstore. Here is the note from his boss, Ben. Jack has to decide what books to order according to the following note and the descriptions of the books.
Hi Jack,
You must hand in the order list of books to me by the first working day of every month. The rules for choosing books are:
For textbooks:
● August is coming. We must choose all textbooks, without thinking of other rules.
For books which are not textbooks:
● If more than five copies of books were sold last month, we choose them. But if there are five copies or more in stock (现货), we do not make an order.
● If the wholesale (批发) prices of the books are higher than $75, we do not choose them. And we do not order anything whose retail (零售) price is higher than $100.
Ben
The descriptions of the books