数列{a_n}是公差不为0的等差数列，a₁=1，且a₃是a₁，a₉的等比中项，则数列{a_n}的通项公式a_n=______．

Soon, more of the information we receive via the Internet could come (31) in digital wrappers.

Wrappers are made up (32) software code that’s targeted to do specific things with the data (33) within them, such as helping to define queries for search engines. They also keep (34) from (35) access to that code.

32（）

A.of

B.off

C.on

D.out