为了避免机械系统发生谐振，变频器采用设置（）的方法。A．基本频率 B．上限频率 C．

阅读理解。

     The famous scientist and thinker, Charles Darwin, was born on February 12, 1809. As a boy,

Charles liked to go for walks in the fields and forests, watching nature, and comparing what he saw

with everything he had read in science books. He also liked collecting very much. He collected many

things: birds, stones, and leaves.

     At sixteen Darwin was sent to Edinburgh University to become a doctor. But he was interested

in the history of nature.

     Then he was sent to study at Cambridge University. There he studied until 1831.

     Some time later he heard that the ship Beagle was going on a trip to South America and wanted a

scientist. His professor advised him to go. So when the Beagle left England in December 1831, Darwin

was on it.

     The expedition lasted almost five' years. Darwin saw many new plants and animals. He collected

all kinds of plants.

     In 1842 Darwin went to live in Kent, and there he continued his studies of change in nature. Darwin

understood that plants and animals are not always the same, and that they really change. By 1859

Darwin had finished his famous book The, Origin of Species. It made a great noise in the world of

science. In 1871 Darwin wrote another important book.

     Darwin continued his studies in science until he died in 1882.

1. Charles Darwin was a great _____ scientist.

A. German        

B. French

C. English          

D. American

2. As a boy, Darwin liked reading _____ books.

A. science          

B. chemistry

C. history          

D. medical

3. Darwin studied at Cambridge University _____ 1831. 

A. after          

B. since

C. before          

D. in

4. On the ship Beagle Darwin worked as a _____. 

A. teacher        

B. doctor

C. professor        

D. scientist

5. In 1871 Darwin wrote another important book _____. 

A. The Origin of Species

B. The Theory of Relativiy

C. The Theory of Evolution(《迸化论》)

D. On Practice

减小残余应力的措施是（）

A、高温时效

B、振动去应力

C、采取粗、粗加工分开

D、全对

胚芽米加工与常规稻谷加工在上工艺有哪些主要区别？

根据《企业破产法》的规定，管理人可以山( )担任。

A．依法成立的律师事务所

B．全体债权人共同

C．依法成立的会计师事务所

D．依法成立的破产清算事务所

化脓性脑膜炎的脑脊液特点

A．压力增高
B．外观毛玻璃状
C．白细胞分类以淋巴细胞为主
D．糖和氯化物升高
E．蛋白质降低