区分天然与充蜡青金石可用（）的方法。
A.测密度
B.测折射率
C.热针测试
D.放大检查
参考答案：C
Mr Brown and his family have _______ Sanya for a few weeks. [ ]
A. been in
B. worked
C. gone to
D. left for
我国女科学家屠呦呦（）年（）月获诺贝尔生物学或医学奖
