水的碱度，根据测定时所使用的指示剂不同或滴定终点的不同，可分为（）
A、活性碱度
B、水解性碱度
C、酚酞碱度
D、甲基橙碱度
参考答案：C,D
括号中所给动词的正确形式填空。
1. It's five o'clock. The students ________ (play) football on the playground.
2. You _______ (not pass) the exam if you don't work hard enough.
3. The baby is sleeping. Could you please stop ________ (make) so much noise?
4. This machine ________ (use) for cleaning the house.
5. The man spoke very slowly. He wanted me ________ (understand) what he said.
镗削平行孔系复杂的主轴箱，一般轴系的同轴度为最小孔公差尺寸的一半，而车床主轴孔的同轴度要求为（）。
A.0.005～0.008mm
B.0.01～0.02mm
C.0.02～0.05mm
D.0.05mm以上
