当活塞运动装置对中不良导致拉缸时，可从（）与（）配合间隙进行分析判断。
A．气缸／活塞
B．气缸／活塞环
C．滑块／导板
D．活塞／活塞环
参考答案：A
用所给词的适当形式填空
1. Do you want________ (make) pumpkin pies with us?
2. My father helped me________(repair) my broken bike,
3. My sister asked me________ (help) her________ (wash)
her clothes.
4. My parents made me________ (stay) at home alone last
night.
5. Mr. Green had his son________ (learn) to play football
when he was six years old.
GB18401-2010《国家纺织产品基本安全技术规范》规定，B类产品pH值为（）。
A．4.0～7.5
B.4.0～8.5
C.3.5～7.5
D.3.5～8.5
