To develop ______, to train themselves to behave logically and truthfully, and to listen and respond to their partners, actors often practice improvisation.

A．may have been
B．that may have
C．may have
D．that may have been

A．To make a plan to celebrate the 50th anniversary of the founding of the Union.
B．To reach a compromise on the controversial new use of employment law.
C．To carry out a massive protests nationwide.
D．To prepare for the national sports meetin