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问题 问答题 简答题

自主神经有何特点？

答案

参考答案：

自主神经的特点为：①支配心肌、平滑肌和腺体的传出神经。②节前神经元不直达效应器，须经外周神经节换神经元，节后纤维才能到达支配的效应器。③不受意识控制，但受精神因素影响。

单项选择题

轴系找中的目的，是要保证两个转子在正常运行状态时的（）要求。

A.同轴度

B.平行度

C.位置度

D.对称度
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单项选择题

Dinosaur expert: Some paleontologists have claimed that birds are descendants of a group of dinosaurs called dromeosaurs. They appeal to the fossil record, which indicates that dromeosaurs have characteristics more similar to birds than do most dinosaurs. But there is a fatal flaw in their argument: the earliest bird fossils that have been discovered date back tens of millions of years farther than the oldest known dromeosaur fossils. Thus the paleontologists’ claim is false.
The expert’s argument depends on assuming which one of the following

A．Having similar characteristics is not a sign that types of animals are evolutionarily related.

B．Dromeosaurs and birds could have common ancestors.

C．Knowledge of dromeosaur fossils and the earliest bird fossils is complete.

D．Known fossils is indicate the relative dates of origin of birds and dromeosaurs.

E．(E) Dromeosaurs are dissimilar to birds in many significant ways.
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