It seems that living green is ______ easy and cheap. A small step can be rewarded with long-term benefits.

A．astonishingly

B．exactly

C．fortunately

D．hardly

在海上货物运输保险中，存在委付现象的前提是发生（）。

A．实际全损

B．推定全损

C．共同海损

D．单独海损