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9401He has finished her homework before he went to bed.
9402Many countries, for example, Mexico and Japan, have a lot of earthquakes.
9403Darwin's most important book, On the Origin of Species, was the result of many years of research.
9404The old lady has just retired from India, where she had lived for ten years.
9405The child needed sturdy shoes which were expensive.
9406You should forgive him for his forgetfulness; after all he is over seventy.
9407The tortoise as far as I know has been on earth for thousands of years.
9408Columbia University the second-largest landowner in New York City is part of the Ivy League.
9409Many students who followed the instructions mechanically failed to obtain satisfactory results.
9410Many villagers, knowing all this, still insisted on my paying for the damage.
9411The castle burnt down a few years ago was never rebuilt.
9412The pilot could hardly find nowhere to land.
9413He has neither talent nor the desire to learn.
9414Do not coin terms that are intelligible to nobody.
9415I think the new political reform will not last barely a month.
9416The desert had scarcely rained last summer.
9417While we were climbing the hill, the rain began to fall.
9418When a small boy, his parents were very strict with him.
9419To swim properly, a course of instruction is necessary.
9420Tearing the curtains apart, there was no one hiding there.
9421After looking out the window for hours, I found the rain passed.
9422Approaching the woods, you will see a cabin.
9423While cleaning his gun, it went off unexpectedly.
9424First rise to your feet and then you should address your guests.
9425Some people like apples, but watermelons are preferred by others.
9426Jenney liked fishing, but hunting was also enjoyed by him.
9427It’s wise for beginning drivers to stay out of heavy traffic until they have more experience.
9428We tried to move around, but there is not too much we can do.
9429People like living in Kunming because they have good weather all year long.
9430I used to think my parents were fussy, but as you grow older, you become more tolerant.
9431I like going out with her because she really made me feel important.
9432The instrument, which was bought by my grandfather, was sent to my house.
9433If you receive from a policeman a request like this, you cannot fail to obey him!
9434The mountains were covered with trees.They were many different varieties.
9435The car drove slowly along the back road.It was quite muddy.
9436Either of the boys may take their bags in the front of the table.
9437Seemingly, neither of them remembered their instruction.
9438There is no doubt that each of us has our own opinions.
9439It is said that if anyone touches the tree, he or she will have bad luck.
9440Playing a musical instrument is a valuable experience for a child.They teach them many important things.
9441It is imperative that every one of us remold our world outlooks.
9442Each and every one of the flowers has their own colors and smells.
9443We grew many different vegetables including cabbages, beans, eggplants, potatoes, tomatoes, and etc.
9444Although it has not yet been finished, I believe it will be carried on.
9445Workers are constructing a building for storage.
9446The reason why he didn’t come is because he was ill.
9447A dog was hit by a car running across the street.
9448They stood in line to buy tickets to the show for twenty minutes.
9449The president　has only two days to stay with his family.
9450The homework scarcely took them an hour to complete.
9451Her employee is a pleasant young woman with a ring named Rebecca.
9452Life was much harder than it is today.
9453There are more students in Class One than in Class Two.
9454I know you better than him.
9455The Yellow River is the second long river in China.
9456This room is as twice large as that one.
9457John is senior to me by two years.
9458No resource is as vital as water.
9459The area of our city is larger than your city.
9460Stephen’s house is so large as John's.
9461Linda is taller of the two sisters.
9462“Oh, that,”he said with a smile as if he was talking about an old friend.
9463The beggar may ask you for money.But he will never asking you to feel sorry for him.
9464The team plans to stay here for five days.During this time, they will give five performances.
9465We'll say goodbye to him, because he’ll away for two months.
9466The searching went on for several weeks, but the murderer was not caught.
9467Pumas, large cat-like animals, are found in America..
9468Lighting the dark sky for a few seconds.
9469Stanley always ready for a fight.
9470I am always nervous on the first day of classes.
9471After I had had lunch at a village pub.I looked for my bag to get money for my bill.
9472The cat maybe on the roof or in the bushes.
9473Broadly speaking, human beings maybe divided into three classes.
9474A strange flying object is seemingly in the backyard.
9475The guy in brown can not trust.
9476The play will soon over.
9477控制系统增加开环极点，通常使根轨迹向（）移动或弯曲，使系统稳定性（），瞬态过程时间（）。
9478180度等相角根轨迹和0度等相角根轨迹，以下哪个绘制规则有区别（）
9479若实轴上两相邻开环极点之间有根轨迹，则它们之间必有（）。
9480若系统型数为2，则以下说法正确的是（）
9481在系统的开环传递函数中增加一个比例微分环节，通常可使根轨迹向（）移动或弯曲。
9482根轨迹与虚轴的交点是系统（）状态时的闭环特征根。
9483对于稳定的系统，增大开环放大系数，其稳态误差会减小。
9484若劳斯阵列中出现全零行，则相应系统一定不稳定。
9485主导极点一定是离虚轴最近的极点。
9486可以通过对开环传递函数进行降阶处理来简化闭环系统的性能分析。
9487若对稳定的系统引入一稳定零点或极点，该零（极）点离虚轴越近，对原系统的动态性能影响越大。
9488采用输出的速度反馈改善二阶系统性能的做法优于偏差的比例微分顺馈方式。
9489对于欠阻尼状态下的二阶系统，其调节时间与峰值时间随阻尼系数的变化规律是相反的。
9490对于稳定的二阶系统，在无阻尼振荡频率固定的前提下，阻尼系数越大，调节时间越短。
9491对于所有系统，增大开环放大系数，其动态性能会变差。
9492一阶系统在单位阶跃输入下的稳态输出值一定为1。
9493拉普拉斯变换将时间函数变换成（）
9494采用系统的输入-输出微分方程对系统进行数学描述是（）
9495对复杂的信号流图直接求出系统的传递函数可以采用（）
9496若系统的开环传递函数为10/(s(5s＋2))，则它的开环增益为（）
9497传递函数反映了系统的动态性能，它与下列哪项因素有关?（）
9498系统的动态性能包括（）
9499直接对控制对象进行操作的元件称为（）
9500与开环控制系统相比较，闭环控制系统通常对（）进行直接或间接地测量，通过反馈环节去影响控制信号
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