【单选题】锌空气燃料电池具有安全、零污染、高能量、大功率、低成本及材料可再生等优点,因而被专家们认为是装备电动汽车等的理想动力电源。锌空气燃料电池,通常以NaCl溶液或NaOH溶液为电解液,锌为负极,空气电极为正极。下列说法正确的是( )
A.
以NaOH溶液为电解液时,电池在工作过程中电解液的pH保持不变
B.
以NaOH溶液为电解液时,负极反应为:Zn+4OH - -2e - →ZnO 2 - +2 H 2 O
C.
以NaCl溶液或NaOH溶液为电解液时,正极反应都为:O 2 +4e - →2O 2-
【单选题】单项选择。 ______ go to the park every Sunday. [ ]
【判断题】the singer is Elvis Presley
【单选题】Presley is _________________ in the history of recorded music. He was commercially successful in many genres, including pop, country, blues, and gospel.
A.
the best-selling solo artist
B.
the best-selling soundtrack artist
C.
one of the best-selling solo artists
D.
one of the best-selling soundtrack artists
【单选题】下列关于Word文档窗口的说法正确的是
B.
可以同时打开多个文档窗口,被打开的窗口都是活动窗口
C.
可以同时打开多个文档窗口,但其中只有一个是活动窗口
D.
可以同时打开多个文档窗口,但在屏幕上只能个文档窗口
【单选题】_____ go to the park every Sunday. [ ]
【单选题】______ are in the same class.