A:分离碘和酒精
B:除去Cl2中的H Cl碘酒
C:收集NO
D:实验室制取NH3
科学探究的基本环节顺序正确的一组是( )
①提出问题②进行实验③作出假设④收集证据⑤分析、归纳得出结论⑥评价.
It is fairly common in Africa for there______ a group of expert musicians surrounded by others who also join in the performances.