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：
