主接地极应在主副水仓各埋设一块，主极地极应用耐腐蚀的钢板制成，其面积不小于（）平方米

根据短文内容选择正确的答案。

      One day, Allan and his friend Henry went swimming in river. It was very hot. How happy they were in the

river! After they got out of the water, they played games in the sun for a while.

      On their way back, Henry saw some flowers. He liked flowers very much and ran into the green field to

look at them. Now Allan was walking by himself.

      Then he heard Henry calling out: " A snake! Help! "

      " What's wrong with you? " asked Allan.

      " A snake bit (咬) me in the leg. Come here! " 

      Allan ran over and saw a small red wound (伤口) on Henry's leg.

      " The snake was in the grass. I didn't see it."

      " Sit down quickly." Allan told Henry. 

      Allan put his mouth at the little red wound and began to suck (吸) at it. In this way he saved (挽救) Henry's

life. " Oh, Allan, it's very kind of you to help me."

      " That's all right. We are friends and we must always help each other."

1. It was ____________ when Allan and Henry went out.[ ]

A. hot

B. cold

C. raining

D. wet

2. After swimming, they played in the sun ____________.[ ]

A. the whole morning

B. for 2 hours

C. long

D. for a while

3. On their way home, ___________ got something wrong with his ____________.[ ]

A. Allan; leg

B. Allan; head

C. Henry; leg

D. Henry; head

4. Henry and Allan are ____________.[ ]

A. workers

B. good friends

C. brothers

D. farmers

5. Which of the following (下面的) is true?[ ]

A. Henry went to look at the flowers' with Allan.

B. Allan saved Henry's life.

C. Allan saw the snake.

D. They ran to the hospital at once.

下列情形中，用人单位不得与劳动者解除劳动合同的有（）。

A、劳动者在本单位患职业病的

B、劳动者患病或者非因工负伤，在规定的医疗期内的

C、女职工哺乳期的

D、劳动者在本单位连续工作满10年的

在微分电路中，若输入信号变化越大，则输出幅度（）

A.越大；

B.不变；

C.越小；

D.不确定。

网络沟通的优势是（）。

A.意义丰富

B.有形，便于核实

C.效率高且廉价

D.快速反馈

个体工商户需增加一个营业执照副本，在业务系统中应进行变更登记业务。