已知数列{an}的前n项和Sn=3n2+8n,{bn}是等差数列,且an=bn+bn+1.
花的主要部分是( )
某研究小组为了验证二氧化碳的部分性质,进行如下实验.
Maria came ____ (猛冲,突进) down the stairs as soon as she heard her mother back home.