套筒阀有何特点?
参考答案:套筒阀特点:由于套筒阀采用平衡型的阀芯结构、阀芯和套筒侧面导向,因此不平衡力小、稳定性好、不易振荡,从而改善原有的阀芯易损坏情况。
用所给单词的适当形式填空。
1. Look! There are two _______ (thief) in the police station.
2. Our teacher teaches us _______ (sing) and English song.
3. We need _______ (she) to teach us Chinese.
4. He often helps me with _______ (me) English.
5. The police _______ (stand) in front of the police station.
某施工机械购置费用为120万元,折旧年限为6年,年平均工作250个台班,预计净残值率为3%,按工作台班法提折旧,该机械台班折旧费为()元。
A.800
B.776
C.638
D.548