解热镇痛药的作用机制是
A.激动中枢阿片受体
B.激动中枢GABA受体
C.阻断中枢DA(多巴胺)能受体
D.抑制PG(前列腺素)合成酶
E.抑制脑干网状结构上行激活系统
参考答案:D
简述烟草的起源及其传入我国的途径?
________, he came to know how great his mother was.
A.From then on
B.From now on
C.Since then
D.Ever since