环境污染物通过食物链的转移并逐级增大在生物体内的浓度,使在高位营养级生物体内的浓度比在低位营养级生物体内的浓度增加很多倍,这种作用称为()。
参考答案:生物放大作用
镇痛药物的治疗不包括()
A.苯二氮类
B.阿片类镇痛药
C.非阿片类中枢性镇痛药
D.非甾体抗炎药(NSAIDs)
E.局麻药
Mary was caught in a traffic jam and by the time she arrived at the airport her father’s plane_______.
A.took off
B.had already taken off
C.was take off
D.had already been taken off