水环泵排真空的过程为（）
A、压缩-排气-吸气
B、排气-压缩-吸气
C、吸气-压缩-排气
参考答案：C
（）around the Water Cube, we were then taken to see the Bird's Nest for the 2008 Olympic Games.
A. Having shown
B. To be shown
C. Having been shown
D. To show
国家如何实施对中小学的管理和监督
