Carl Linnaeus, the famous botanical scientist, was a man always in blue. His depression was

       his childhood illness in his biography.

A．centered on              B．concentrated on            C．named after               D．referred to

Carl Linnaeus, the famous botanical scientist, was a man always in blue．His depression was ________ his childhood illness in his biography．

1. A.
   centered on
2. B.
   concentrated on
3. C.
   accustomed to
4. D.
   referred to