一群处于n=4的激发态的氢原子,(1)跃迁时可能发出的谱线有 条? (2)已知氢原子基态的能级为E1,在这些光谱中写出最长的波长表达式λ= 。
(1)6 (2)-144hc/7E1
根据汉语意思或首字母提示,填写适当的单词。
1. The weather during our holiday was p________.
2. After a time, you get to ________ (认识到) the importance of English study.
3. It's i________ for man to go to the sun.
4. We used to go to the c________ once a week.
5. They are still ________ (搜寻) for the missing child.
缺乏下列哪种元素会造成血清胆固醇降低()
A.铁
B.铜
C.铬
D.锰
E.锌