在生物化学实验中可能成瘾的药物有()
A.安非他明
B.吗啡
C.可卡因
D.大麻
E.冰毒
参考答案:A, B, C, D, E
The old couple have been married for 40 years and never once _____ with each other. [ ]
A. they had quarreled
B. they have quarreled
C. have they quarreled
D. had they quarreled
地形是通过对光照、温度、水分和养分等重新分配对生物生长产生影响,因而它是______生态因子。