钻井现场，应严格执行钻井液处理规程，补充水，胶液或加重时，均应按小样分析结果所计算需补充量，在一个循环周期内均匀加入，并且有人在旁监护。
参考答案：对
根据句意补全单词.
1. Thank you for j________ CCTV's " Around the World " show.
2. Some are t________ photos of the great buildings.
3. Look at this group of people p________ beach volleyball.
4. How's the weather? It's c________.
5. What is the weather like? It's r________.
为了使电机的旋转速度减半，变频器的输出频率必须从60Hz改变到30Hz，这时变频器的输出电压就必须从400V改变到约（）V。
A.400
B.100
C.200
D.220
