It is said that his new book consists of nine chapters.
A:is made up of
B:is connected to
C:is covered with
—We just had a terrible accident.
—________But it's good to see you are all right.( )
现有m g某气体,它由双原子分子构成,它的摩尔质量为M g•mol﹣1.若阿伏加德罗常数用NA表示,则: