下列关于能层与能级的说法中正确的是( )
A:原子核外电子的每一个能层最多可容纳的电子数为2n2
B:任一能层的能级总是从s能级开始,而且能级数不一定等于该能层序数
C:同是s能级,在不同的能层中所能容纳的最多电子数是不相同的
D:1个原子轨道里最多只能容纳2个电子,但自旋方向相同
自从用上沼气,村民做饭便告别了传统的“烟熏火燎”,一座8﹣10立方米的沼气池,一年的产气量达320﹣350立方米,相当于给每户沼气池用户节约800元左右的能源经费.在一个人工农业生态系统中,鸡、猪、人的粪便以及玉米秸秆放入沼气池,产生的沼气用于照明和做饭,沼渣可以做肥料.请分析回答以下问题:
解释下列划线词语。
①黯然
②追
判断下列句子是否与短文相符。
Hello, my name is Tom. I'm a pupil. I go to school from Monday(星期一) to Friday(星期五). I have six lessons a day. Four in the morning and two in the afternoon. From 11:20 a.m. to 1 p.m., I have a lunch break.Today is Tuesday(星期二). I have Chinese, Maths, Music and PE in the morning. And I have Science and Art in the afternoon. I like PE and Art. I likeplaying football in the playground. Art is fun. I like drawing. I can draw nice picture. My sister likes Art too. We join the art club together.