Nowadays senior high students are burdened with too many         ,which is making them less

and less confident.[ ]

A. motivations

B. expectations

C. amusements

D. opportunities

基于分子外层价电子吸收一定能量后，由低能级跃迁到较高能级产生的吸收光谱（）

A.红外吸收光谱

B.荧光分析法

C.紫外-可见吸收光谱

D.质谱

E.电位法