________ theme of the Shanghai Expo is “Better city, better life”． It will send _____ message to people around the world to care about the places where they live．

A．/…a

B．The…a

C．A…the

D．/…the

在空气中用波长为λ的单色光进行双缝干涉实验，观察到相邻明条纹间的间距为1.33mm，当把实验装置放入水中（水的折射率为n=1.33）时，则相邻明条纹的间距变为（）。

A.1.33mm

B.2.66mm

C.1mm

D.2mm