—Do you remember _______ vase I gave you as a birthday gift last year?

—Yes, I fell in love with it at _______ first sight.

A．a; the

B．a; /

C．the; the

D．the;/

有甲、乙两个不同浓度的同一有色物质的溶液，用同一厚度的比色皿，在同一波长下测得的吸光度分别为：甲0.20；乙0.30。若甲的浓度为4.0×10mol/L，则乙的浓度为（）

A.8.0×10mol/L

B.2.0×10mol/L

C.4.0×10mol/L

D.6.0×10mol/L

E.3.0×10mol/L