YB55型小盒透明纸包装机操作人员按下（）显示按钮，允许操作者选择在OPC终端按显示

已知a>0，若a²+a^-2=7，则a+a^-1=（    ）。

阅读材料和漫画《上学路上》，给漫画配首诗歌，要求押韵。(4分)

一趟活儿，顾客上车下车没用两分钟，而计程表显示里程仅为680米——如果您是位的士司机，每天遇上这样的事，将有何感想？这不，广州市天河区的的哥们就屡屡接到电话，将某实验学校的学生接回几百米外小区内的家。

答：________________________________________________________________________

金属钠、氯气和二氧化氮共同具备的化学性质是[ ]

A. 与水反应　　

B. 与氯化钾反应

C. 与硫酸反应

D. 与二氧化碳反应

阅读理解。

     On Easter Day, 1722, Dutch explorers (探索者) landed on Easter Island (复活岛). It was the first

time that Easter Islanders had met people from the outside world. The strangers were about to discover

something very strange themselves -that they were on an island with hundreds of huge stone statues (雕像). The Dutch explorers wondered where the Islanders had come from and why and how they had built

the statues. Now science is putting together the story.

    The first people to arrive on the island came there around A.D. 700. The society that developed there

was based on fishing and farming to feed the population, which grew to 12,000. Its success showed itself

in a way that has become the island's trademark (标记): hundreds of huge stone figures -the moai.

    None of the moai was standing when scientists first arrived. People put them back up later; but how

had a Stone Age society ever made, moved and set them up there in the first place? And why?

    There are nearly 900 moai on Easter Island, and while the questions about them remain unanswered, no one doubts the years of effort that must have gone into making them.

    The real killer of the Easter Islanders came from across the ocean. After 1722, it became popular for

explorers to visit Easter Island, bringing diseases. The final blow (打击) came in 1862, when slave traders came from Peru and took away 1,500 people, one-third of the population.

1. Before the Dutch explorers arrived on Easter Island, _____.

A. Easter Island was separate from the outside world

B. they knew where Islanders had come from

C. they discovered something dangerous    

D. the huge stone statues were upright

2. When the first explorers arrived on the island, they _____.

A. were frightened by the huge stone statues

B. were surprised by what they saw

C. set many of the moai on the island upright

D. fished and farmed

3. All researchers agree that _____.

A. the natives could hardly support themselves

B. the moai must have taken a great effort to make

C. the Islanders mainly died of diseases brought by explorers

D. the explorers helped the Islanders live better lives

4. The passage implies that _____.

A. the Islanders built the moai to show off their success

B. the Dutch explorers discovered how the moai had been built

C. in 1862, before slave traders came, about 4,500 people were living on Easter Island

D. the natives of Easter Island have been there for about 1,200 years

5. "The real killer" in the last paragraph refers to _____.

A. the slave traders              

B. the scientists

C. the explorers                

D. the moai

涂料的遮盖力是由（）提供的。

A.颜料

B.树脂

C.溶剂

D.体质