While the causes of the Cretaceous-Tertiary extinction have received the most attention, Alvarez’s paper points out work on the other major mass extinctions that may also be（）for the tragedy.

A．Adaptive Visual Metamorphosis in Deep-Sea Vent Crabs
B．Aspects of the General Anatomical Development of Deep-Sea Vent Crabs
C．New Research Directions in the Study of Deep-Sea Vent Crabs
D．Common Features of Optics of Lower Depth Oceanic Animals
E．Patterns of Anatomical Transformation in Lower Oceanic Creatures

A．obstinate ； infuriate
B．obedient ； refute
C．refractory ； provoke
D．intractable ； remonstrate
E．bizarre ；palliate