Scientific research shows that animals can showemotions like human beings. They are somet

问题补充：

Scientific research shows that animals can showemotions like human beings. They are sometimes lively, and sometimes bad-tempered.

A. contradictory

B. instant

C. appropriate

D. flexible

答案：

A. contradictory

B. instant

C. appropriate

(答案→)D. flexible

解析：考查形容词。A．contradictory矛盾的；B．instant立即的；C．appropriate适当的；D．flexible灵活的。句意：科学研究表明，动物可以显示像人类一样灵活的情感。它们有时活泼，有时坏脾气。故D正确。