500kv线路至路面的最小垂直距离为（）

 自然界存在NaIO₃，可利用NaIO₃与NaHSO₃溶液来制取单质碘。反应分两步进行：IO₃^-+3HSO₃^-=I^-+3SO₄^2-+3H⁺；IO₃^-+5I^-+6H⁺=3I₂+3H₂O。下列说法错误的是（  ）

A．NaIO₃是氧化剂， HSO₃^-是还原剂

B．生产中可得到副产物H₂SO₄和Na₂SO₄

C．I₂既是氧化产物又是还原产物

D．HSO₃^-的还原性比I^-弱

《都城纪胜·市井》记载，南宋杭州城“其夜市除大内前外，诸处亦然，惟中瓦前最胜，扑卖奇巧器皿百色物件，与日间无异。其余坊巷市井，买卖关扑，酒楼歌馆，直至四鼓后方静；而五鼓朝马将动，其有趁卖早市者，复起开张。无论四时皆然。”这反映了当时该城(    )

A．商业活动只在白天进行

B．商业活动受时间和空间限制较小

C．售卖的商品种类单一

D．售卖的商品主要满足皇室的需要

阅读理解。

     One morning more than thirty years ago, I entered the Track Kitchen, a restaurant where everyone from

the humblest (卑微的) to the most powerful came for breakfast. I noticed an empty chair next to an elderly,

unshaven man, who looked somewhat disheveled. He was wearing a worn-out hat and was alone. I asked if

I might join him. He agreed quietly and I sat down to have my breakfast.

     We cautiously began a conversation and spoke about a wide rang of things. We never introduced ourselves.

I was concerned that he might have no money and not be able to afford something to eat. So as I rose to go

back to the counter and buy a second cup of coffee, I asked,

     "May I get you something?"

     "A coffee would be nice."

     Then I bought him a cup of coffee, We talked more, and he accepted another cup of coffee. Finally, I rose

to leave, wished him well, and headed for the exit. At the door I met one of my friends. He asked,

     "How did you get to know Mr. Galbreath?"

     "Who?"

     "The man you were sitting with. He is chairman of the Board of Churchill Downs."

     I could hardly believe it. I was buying, offering a free breakfast, and feeling pity for one of the world's

richest and most powerful men!

     My few minutes with Mr. Galbreath changed my life. Now I try to treat everyone with respect, no matter

who I think they are, and to meet another human being with kindness and sincerity.

1. What does the underlined word "disheveled" mean? [ ]

A. Unfriendly.

B. Untidy.

C. Gentle.

D. Kind.

2. The author bought coffee for the old man because _____.[ ]

A. he thought the old man was poor

B. he wanted to start a conversation

C. he intended to show his politeness

D. he would like to thank the old man

3. How did the author probably feel after he talked with his friend? [ ]

A. Proud.

B. Pitiful.

C. Surprised.

D. Regretful.

4. What is the message mainly expressed in the story? [ ]

A. We should learn to be generous.

B. It is honorable to help those in need.

C. People in high positions are not like what we expect.

D. We should avoid judging people by their appearances.

国际收支平衡表的项目内容包括（）。

A.经常项目

B.资本和金融项目

C.净误差与遗漏

D.储备资产

E.其他

加入溴冷机组的热量和从机组带出的热量应相等或相近，即投入产出应达到平衡，这就是溴冷机的（）。

A.等热率

B.热均率

C.热平衡

D.冷热平衡