However，at times this balance in nature is _______ resulting in a number of possibly unforeseen effects.

A．troubled

B．disturbed

C．confused

D．puzzled

欧共体成立的主要目的是

A．联合起来与美国争夺世界经济霸权

B．加快经济发展

C．实现政治一体化

D．抵制美苏的“冷战”