属于WHO专家推荐的镇痛三阶梯方法中第一阶梯药物的是：（）
A.可待因
B.强痛定
C.阿司匹林
D.曲马多
E.吗啡
参考答案：C
If Newton lived today, he would be surprised by what ______ in science and technology. [ ]
A. had discovered
B. had been discovered
C. has discovered
D. has been discovered
