DNA的基本组成单位是[ ]
A．氨基酸
B．脱氧核苷酸
C．核糖核酸
D．脱氧核糖
答案：B
All people, ____they are old or young,black or white,all hold the same dream to have a peaceful world.
A．whether
B．however
C．no matter
D．even though
配置M断路器的ATS电源自动切换系统时需特别注意什么？
