A:印刷术
B:造纸术
C:指南针
D:火药技术
常见金属R与硝酸银溶液反应的化学方程式为R+3AgNO3==3Ag+R(NO3)3,有关该反应的说法正确的是
对下列生物或结构进行化学成分分析,最相似的是( )
根据句意及首字母提示完成单词
(1) My favourite drink is orange j____ .
(2)Fruit and v____ are good for our health.
(3)He is thirsty (口渴的). He drinks lots of w____.
(4) What k____ of fruit have you got?
(5)I like eating fish. It's very d____.
当北半球是冬季时,南半球的季节是( )