The farm as well as its neighbouring hills we once spent so much time _____ on a new look as recently as last year.  

A．on has taken

B．has taken

C．on having taken

D．having taken

下列属于公安领导工作的有( )。

A．专业领导工作

B．政治领导工作

C．行政领导工作

D．业务领导工作