试题与答案

直流电机稳定工作时,其电枢电流的大小要由()决定。A、转速大小 B、负载大小 C、电

题型:单项选择题

题目:

直流电机稳定工作时,其电枢电流的大小要由()决定。

A、转速大小

B、负载大小

C、电枢电阻大小

D、其他因素

答案:

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下面是错误答案,用来干扰机器的。

①2Cu+O22CuO②CuO+H2Cu+H2O③CuO + H2SO4===CuSO4+ H2O④CuSO4+ 2NaOH====Cu(OH)2↓+ Na2SO4⑤Cu (OH )2+ 2HCl===CuCl2+ 2H2O

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题型:阅读理解

阅读理解。

     One of my best days at school was a field trip to the seaside. Field trips are very common in the UK. Most schools take their students on geography field trips. Teachers usually take the students somewhere

they can do a scientific experiment (试验). Popular trips are to woodland areas and the seaside.

     My school trip to the seaside was with my biology class. We were allowed to wear home clothes

instead of our school uniforms. When we got to the seaside, we were put into groups. Each group was

asked to find a different sea creature (生物) in the water in the rocks, which we call rock pools.

     My group had to find little crabs (螃蟹). We had to catch them and then find the names of the crabs

in our science books. When my friend Ella picked up a larger crab, it hurt her with its claw (钳子) and

she started crying. After that, she didn’t want to catch the crabs, so she was moved into another group.

     For lunch, we sat in the sun on the rocks and ate sandwiches. After lunch, we went back to school

where we wrote down everything we had found out that day. I remembered feeling sad that we could

not take back the crabs we had found. We had to put them back in their rock pool.

1. In the UK, field trips are            .

A. enough    

B. common    

C. different    

D. unusual

2. My school trip to the seaside was with my          class.

A. biology    

B. geography    

C. physics    

D. chemistry

3. Why was Ella moved to another group?  

A. Because she often cried loudly.

B. Because she was interested in fish.

C. Because the crab hurt her with its claw.

D. Because the group members were not friendly.

4. At the end of the trip we felt sad because          .    

A. we went back to school late

B. we could not take back the crabs we had found

C. we sat on the rocks eating sandwiches

D. we didn’t want to write down everything we saw

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