Shellfish give the deceptive appearance of enjoying a peaceful existence, although in fact life is a constant struggle for them（）.

单项选择题It was rather strange how the habits of his youth clung to him still. He was 72（）.

A．stuck to
B．turned
C．led to
D．gave way to

单项选择题Public relations practice is the deliberate, planned and sustained effort to establish and maintain mutual understanding between an organization and its public（）.

A．complete
B．related
C．intentional
D．active