With more and more birds _______, some day some species will _______ completely. In addition, some of them have _______ environmental pollution.

A．dying off; die out; died from

B．dying away; die off; died from

C．dying down; die out ; died of

D．dying out; die away; died of

科目 英语   题型 单选题   难度 中等

知识点： 一般将来时的被动语态 完成对话 谓语