12. The company ____ in the import and export of food and medicine enjoys a high reputation internationally. Their company is an enterprise ________ in the import and export of food and medicine. A)specialized B) specializing C) having specialized D) being specialized 答案:B为证实叶绿体有放氧功能,可利用含有水绵与好氧细菌的临时装片进行实验,装片需要给与一定的条件,这些条件是( )
A.光照、有空气、临时装片中无NaHCO3稀溶液
B.光照、无空气、临时装片中有NaHCO3稀溶液
C.黑暗、有空气、临时装片中无NaHCO3稀溶液
D.黑暗、无空气、临时装片中有NaHCO3稀溶液