原子荧光光谱和原子吸收光谱仪在结构上的主要区别是（）
A.光源
B.光路
C.单色器
D.原子化器
参考答案：B
The news of ________ greatly made us surprised a lot as he was indeed very excellent.
A．not his having elected
B．not his being elected
C．his not being elected
D．his not having elected
女性，49岁。进食哽噎感6个月，加重伴消瘦1个月。食管吞钡X线造影检查：食管下段贲门处狭窄，黏膜破坏。诊断首先要考虑（）。
A.食管癌
B.食管腐蚀性狭窄
C.贲门失弛缓症
D.食管炎
E.食管痉挛
