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【判断题】
两台型号相同的泵串联操作时,每台泵的流量和压头也各自相同。串联泵的工作点由合成特性曲线与管路特性曲线的交点决定。两台泵串联操作的总压头必低泵压头的两倍,流量大泵的。串联泵的效率为 Q 串 下单台泵的效率。A.
正确
B.
错误
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【简答题】9-31 已知两方向同频率的简谐振动的运动方程分别为 , ,式中 的单位为m,t的单位为s.求: (1)合振动的振幅及初相; (2)若有另一同方向同频率的简谐振动 ,式中 的单位为m,t的单位为s,则 为多少时, 的振幅最大?又 为多少时 , 的振幅最小?
【单选题】He is now a teacher and a ( ) member of the community.
A.
respectful
B.
respecting
C.
respective
D.
respectable
【简答题】Mr Green is our foreign teacher . He is a good teacher . He often helps us a lot .And he is nice to every student . His lessons are very interesting . We usually have fun in his lessons . We all like ...
【简答题】两同方向同频率简谐振动的合成,已知振动方程分别为 则合振动的振幅为 cm
【简答题】根据短文内容,选择正确答案。 Sam is a teacher of maths. He is not young, but he is not old. He is 40 years old. He has a round (圆的) face and black hair. He is short. There are forty students in his class. They all ...
【单选题】He ________ in a foreign trade company for five years, but he now is a volunteer teacher in a village.
A.
had worked
B.
worked
C.
works
D.
has worked
【简答题】简述教育管理的特殊性。
【简答题】Mr Green is our foreign(外国的)teacher．He is a good teacher．He often helps us a lot．And he is nice to every student．His lessons are very interesting．We usually have fun in his lessons．We all like him． He...
【简答题】简述教育管理区别于一般社会管理的特殊性。
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