当部分激动剂与达Emax的激动剂合用时,前者表现为()
A.激动作用
B.相加作用
C.拮抗作用
D.无影响
E.相反作用
参考答案:C
依据《全国生态环境保护纲要》,下列区域不属于重要生态功能区的是()。
A.防风固沙区
B.农作物种植区
C.江河洪水调蓄区
D.水土保持重点监督区
She said she____________ me five letters in one month[ ]
A. has written
B. will write
C. had written
D. wrote